This number is a prime.
Just showing those entries submitted by 'Leonardis': (Click here to show all)
2531 = 7^3 + 1 + 3^7. [Leonardis]
(There is one curio for this number that has not yet been approved by an editor.)
Printed from the PrimePages <primes.utm.edu> © G. L. Honaker and Chris K. Caldwell