Primality proof for n = 68477:
Take b = 2.
b^(n-1) mod n = 1.
53 is prime.
b^((n-1)/53)-1 mod n = 67193, which is a unit, inverse 38025.
19 is prime.
b^((n-1)/19)-1 mod n = 60449, which is a unit, inverse 62890.
(19 * 53) divides n-1.
(19 * 53)^2 > n.
n is prime by Pocklington's theorem.