83

This number is a prime.

(83, 89, 97) is the larger of only three known cases of successive primes p < q < r such that p|(qr-1), i.e., the smallest prime divides the product of the other two minus 1, (83 divides 89*97-1). The previous two cases are (2, 3, 5) and (11, 13, 17). [Loungrides]