12721

This number is a prime.

The smallest palindromic prime p such that (p+1)/2 and (p+2)/3 are also prime. [Russo]

The smallest prime p where p+1=2*prime, p+2=3*prime, and p+3=4*prime. [Marot]

A palindromic prime that is one more than the sum of the numbers 1 to 159. [Green]

Smallest palindromic prime such that product of its digits is a perfect number. [Gupta]