Dorky Poll: Favorite Prime Number?

A pretty straightforward question: Which prime number do you like the best?

This is a purely classical poll, so you only get to choose one favorite, not a superposition of multiple numbers. Your selection is legally binding, so choose wisely!

(There’s actually a point to putting this up today, beyond providing some cheap and easy blog traffic… I’ll explain later.)


  1. #1 marciepooh
    January 20, 2011

    37 – the next prime age I’ll be

  2. #2 andre3
    January 20, 2011

    1. Oh yeah, I went there.

  3. #3 cisko
    January 20, 2011

    I’m glad I’m not the only one who treats prime ages as milestones. What’s so enchanting about multiples of 10?

    As you get older, you get fewer and fewer of them though. That’s appropriate — after you’ve had a few birthdays, they start to lose their luster — but it’s also kind of sad.

  4. #4 Neil B
    January 20, 2011

    Tx, these are cute polls and I like the concept work like for 43. In physics, may favorite prime is indeed 137 which is closest to inverse of alpha the FSC (not exact!) I dig that because as a fundamental dimensionless constant it “ought” to make logical sense directly if the universe is logically oriented in theoretical constructs. So it should be e.g. “one” – but instead it’s that ugly number of no clear conceptual significance, *but* it does have significance as an anthropically beneficial value that makes the universe more hospitable to life. That should still be taken as an interesting feature, whatever your conclusions are if any (see more at the name link.) Of course as well should all know, any particular universe existing and not other possible worlds violates the logical principle of sufficient reason … So either they all exist like modal realism/MUH, or Something or “SomeOne” decides what does and what doesn’t, like it or not IMHO.

    But “socially” my favorite prime is the magically mysterious occult number 23 as promoted by Robert Anton Wilson cultists and oc-cultists. Yeah, it’s more cool than “13” IMHO, it’s the classier step up. (OK: 23:13 :: Gaga:Ke$ha!) Whatever you think of that shtick, it’s fun!

  5. #5 Emory Kimbrough
    January 20, 2011

    2011 = 157+163+167+173+179+181+191+193+197+199+211

    So, 2011 is not only a prime number, it’s the sum of consecutive prime numbers. On closer inspection, it’s the sum of a prime number of consecutive prime numbers.

    Next year, I’ll need to find a new favorite, though.

  6. #6 chrisj
    January 20, 2011

    So, bonus geek-point for the Tolkien ref, but I’m going to have to fine you for not mentioning the rule of five (medical or Discordian version; either is fine with me).

  7. #7 Blaise Pascal
    January 20, 2011

    Hmmm, as I write this, 9 people including myself claim they would identify their “other” in the comments, yet there are no comments…

    17 is of course the most random number.

  8. #8 Eric Lund
    January 20, 2011

    17. Everybody’s favorite “random” number.

  9. #9 mcxxiii
    January 20, 2011


    I could have said 11 and I could have said 23, but they’re only really special when paired.

  10. #10 quasihumanist
    January 20, 2011

    As a mathematician, I cannot have favorite numbers for fear that all the other numbers will feel neglected and turn feral on me.

  11. #11 Don
    January 20, 2011

    My amps go to ELEVEN!

  12. #12 David
    January 20, 2011

    I just love 7. It’s the only number I know that can only be divided by itself and 1. Err and uh 7. And 5. And thinking about it 11 as well and er 3. Possibly 2 can as well as 9. Hang on, no, 9 divides by 3. So, other than 2,3,5 and 11, only 7 counts. Err and 13…. What exactly did the Romans do for us?

  13. #13 Nathan Williams
    January 20, 2011

    10288065751. It’s an eleven-digit prime, which is fun in its own right, but more importantly, it’s 123456789012 / 12, and thus one of the largest prime numbers one is likely to discover while bored in class with an HP-32.

  14. #14 Richard Edgar
    January 20, 2011

    63265777. When we were in junior high school, and learning about factoring, a friend cobbled up a 12-digit number (all the calculators could handle) for us to factor. We borrowed a prime number table that went up to 1000 from the teacher, and still nothing. Turned out one factor was the above, and the other was 1613. I typed that number into calculator keyboards often enough that I’ll never forget 102047698301. I can’t learn phone numbers any more, but I do remember that.

  15. #15 Anonymous Coward
    January 20, 2011

    6 – the other even prime number!

  16. #16 Wilson
    January 20, 2011

    I guess it falls to me to point out Sheldon Cooper’s favourite, which isn’t on the list. I haven’t decided if it’s my favourite, too.

  17. #17 Wilson
    January 20, 2011

    Damn, I screwed up that link tag. Sorry.

    This one works.

  18. #18 Alex Besogonov
    January 20, 2011
  19. #19 JMc
    January 20, 2011

    47. No real reason why, I just like it.

  20. #20 Steven Colyer
    January 20, 2011

    3139971973786634711391448651577269485891759419122938744591877656925789747974914319422889611373939731 is a 100-digit prime, and it’s prime whether it’s listed forward or backward. Further, if it’s arranged in a ten by ten matrix, through and through – reversible primes.

    … each row, column, and diagonal is itself a reversible prime.

    Discovered by Jens Kruse Andersen.

    I wish I figured that out by myself, but I must give credit where credit is due. Our fellow American Pat Ballew, who teaches Mathematics to people at a US Defense Department base near Cambridge in the UK, taught me that. You can see the matrix at his blog post: here.

  21. #21 Steven Colyer
    January 20, 2011

    Oops, the number was cut off, much like Physicists do with infinities, unlike we Engineers, who according to you have “9” as a fav prime number. Why so cheeky? Are you afraid of the competition? I’m putting you on notice that I’m reporting you to The Engineering Anti-Defamation League. Expect to be pelted with 45-degree and 30-60 triangles any day now. Maybe a French curve for flavor.

    Here’s the number in 2 50-digit manageable bits:


  22. #22 Arend
    January 20, 2011

    17–Gauss Heptadecagon!

  23. #23 joemac53
    January 20, 2011

    109. My youngest daughter rides horses that jump over fences and gets numbers for various shows. She rolls her eyes when I tell her a number id good because it is a perfect square, or has only single power factors, etc. She thought she could get away with 109, but “it’s Prime!”

  24. #24 23
    January 20, 2011

    I was asked this question as a pick-up line recently.
    Not very effective, but memorable.

  25. #25 Nirav
    January 20, 2011

    The first 38 digits of π are prime:


    I’m still amazed by the 100-digit prime (comment 20)! wow.

  26. #26 Mary Aileen
    January 20, 2011

    17. Just because.

  27. #27 Cath the Canberra Cook
    January 21, 2011

    17. The random prime.

  28. #28 Sili
    January 21, 2011

    Chalk another one up for 17.

    Thanks for making fun of engineers instead of chemists.

    I seem to recall a poll that determined that everybody’s favourite prime that isn’t a prime is 39, but I may be mistaken.

  29. #29 darwinsdog
    January 21, 2011

    1 is my favorite prime number. I’ve been told that it isn’t really prime but I don’t believe it. Seems like it ought to be prime to me so I say it is prime. What other numbers can it be evenly divided by besides 1 & itself? I don’t think there’s an infinite number of prime numbers, either. How could Euclid be so sure there is? Did he count them? Did he make an infinitely long list of prime numbers? I don’t think so. Sure, there’s a lot of them but I think they run out somewhere in the kazillions, or tens of kazillions.

  30. #30 Neil B
    January 21, 2011

    Darwinsdog, Euclid was very clever and figured out how to prove there is no highest prime number. He reasoned using a reductio ad absurdum or self-contradiction proving the converse (as for the proof that square root of two is irrational): suppose there was a highest prime number. That means we can make a product of all of them together and then add one, like 3*5*7*11*13*17 …*P_last + 1. Call that number E. Then try to factor E into primes itself, which we should be able to do since it’s bigger than the alleged “biggest prime.” But if you try, dividing E by each available prime used to construct it, you will of course have a quotient made of other primes multiplied plus some fraction like 1/13, etc, for each one you try to use (and using more just makes it worse.) Hence there can be no biggest prime. These ancient greats were very clever thinkers.

  31. #31 vinceh
    January 21, 2011

    101, just because.

  32. #32 Steven Colyer
    January 22, 2011

    #25: Navda wrote: I’m still amazed by the 100-digit prime (comment 20)! wow.

    That is pretty crazy. I’d have been impressed if the number broken up in just ten bits were all primes. But, backwards and forwards AND vertically backwards and forwards AND diagonally backwards and forwards both ways? What the … ??

    Even more impressive is that someone FOUND that!

    Extra credit: How many 100-digit primes are there?

    My favorite Prime is 3. It appears in physics far out of proportion than it should. Albert Einstein (wave-particle) and Emmy Noether (symmetry-conservation laws) got us started on the concept of duality, but increasingly triality is being investigated by theoretical physicists.

  33. #33 Steven Colyer
    January 22, 2011

    I meant #25: Nirav. Sorry, and yes that’s amazing as well that all those first digits of pi form a Prime. But what does it all mean?

    The Clay Mathematics Institute offers a one million dollar award for solving Riemann’s Hypothesis, which relates Primes and the Zeta function. Any takers?

  34. #34 Sili
    January 22, 2011

    The first 38 digits of π are prime:


    I’d be more impressed if no truncation of π resulted in a prime.

  35. #35 Louis
    January 24, 2011

    41, because the the answer to life, the universe and everything is 42.

  36. #36 largo
    May 20, 2011

    1 + 2i. My favorite prime factor of 5.

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