16950...64007 (1172-digits)
This number is a probable-prime (likely to be a prime but we have not (re-)proven it on this site).
As of 2018, the largest known titanic prime of the form Sigma(Fermat prime^n) = 257^486. Certified prime by Primo. [Sariyar]
Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell