Primality proof for n = 73868779472585473:

Take b = 2.

b^(n-1) mod n = 1.

123127 is prime.
b^((n-1)/123127)-1 mod n = 45517493766363079, which is a unit, inverse 23069660899873360.

43319 is prime.
b^((n-1)/43319)-1 mod n = 1894363730941191, which is a unit, inverse 72625644443242174.

(43319 * 123127) divides n-1.

(43319 * 123127)^2 > n.

n is prime by Pocklington's theorem.