**121**= 11 x 11.

**121**is the smallest multidigit palindromic square. It is also the smallest palindromic composite such that some permutation of digits is prime. It is the only odd palindromic square with an odd number of digits that is divisible by a palindromic prime number with an even number of digits.

**121**is a perfect square. It is also a centered octagonal number and a centered dodecagonal number.

Every number greater than

**121**is the sum of distinct primes of the form 4

*n*+ 1.

**121**is 11111 in base 3.

**121**is the maximum number of regions into which 15 lines divide a plane.

**121**can be expressed as the sum of a prime and its reversal for exactly three distinct primes:

**121**= 29 + 92 = 47 + 74 = 83 + 38.

**121**= 1 + 3

^{1}+ 3

^{2}+ 3

^{3}+ 3

^{4}.

**121**is the number of points required to win a standard game of cribbage.

Source: Prime Curios!