173

This number is a prime.

173 is a curious prime which occurs twice in the properties of the curious prime 30103, as found by Jud McCranie and G. L. Honaker, Jr., in July 1998. 30103 is the only known multidigit palindromic prime found by averaging the divisors of a composite number: 30103 = (1 + 5 + 173 + 865 + 29929 + 149645)/6 and 30103 = (1 + 2 + 3 + 6 + 173 + 346 + 519 + 1038 + 29929 + 59858 + 89787 + 179574)/12. 30103 = average of divisors of 149645 and 30103 = average of divisors of 179574. [Post]