111 = 3 x 37.
111 is the smallest palindromic number such that the sum of its digits is one of its prime factors.
111 is a number that cannot be written as a sum of three squares.
A six-by-six magic square using the numbers 1 through 36 has a magic constant of 111.
111 would be the magic constant for the smallest magic square composed only of prime numbers if one were counted as a prime.
In J.R.R. Tolkien’s The Lord of the Rings, Bilbo Baggins disappears from his eleventy-first (111th) birthday party and from the Shire.
Sources: Number Gossip