37111337

This number is a prime.

37111337 is prime. Split the digits into 4 pairs (37, 11, 13, 37) and all of them are prime. Now split the first pair into two digits (3, 7) and multiply with the remaining pairs (3 * 7 * 11 * 13 * 37) to get 111111. Note that 3 * 37 = 111, which is embedded in the original prime. [Brod]