3121

This number is a prime.

The smallest solution to the famous puzzle that first appeared in Ben Ames Williams's "Coconuts" from The Saturday Evening Post (October 9, 1926). [Poo Sung]

The only non-titanic emirp equal to the form p^p-q^q, where p, q, are primes (case p=5, q=2). [Loungrides]

The only non-titanic emirp of form x^x-x+1, case x=5. Note that there are only two other primes, (x=2, x=13) that create non-titanic primes of this form. [Loungrides]

The dental formula for the lower teeth of an adult domestic cat. [Honaker]

The smallest case of a squared and cubed reversal of a prime that yield primes. [Petrov]