This number is a composite.
A curious palindrome whose splitting up into parts 7 and 17 is interpretable in two ways. First as 'the 7th prime is 17' and secondly as 'the sum of the primes up to 7 is 17'. No larger palindrome is known having this two-fold property. [De Geest and Rosa]
717 is the largest three-digit palindrome such that if it is raised to the sum of its digits plus the sum of its digits plus one, the result is prime. I.e., 717^(7+1+7)+(7+1+7)+1 is prime. [Opao]