10000...00153 (500-digits)

This number is a prime.

10^499+153 is the smallest 500-digit prime. Note that the concatenations: 153499 is prime and 499153 is a brilliant number, i.e., 499153 = 617 x 809, with the concatenation in order of its prime factors, i.e., 617809, being a prime. [Loungrides]