2311

This number is a prime.

The 23rd of November is the only date which can be read as a prime in both formats: 'day-month' and 'month-day'. [Kik]

The last primorial prime (p# + 1) in which its square root is less than p^2, i.e., 2311^(1/2) ~ 48 < 121 = 11^2. [Nicholson]

The concatenation of the first three prime Ulam numbers (2,3,11) is a prime. [Gupta]

The largest member in a set of twin primes generated by the formula 30(n*(n+5)/2)+60 +1 and -1, for N = 0 to 10. [Homewood]