19

This number is a prime.

Just showing those entries submitted by 'Patterson': (Click here to show all)

19^19 - 2 is prime. Note that it starts with the digits 19. [Patterson]

The smallest prime p such that p^p is pandigital. [Patterson]

The only two-digit prime n such that n!/reversal(n)+1 and n!/reversal(n)-1 are both prime. [Patterson]