Primality proof for n = 108140989558681:
Take b = 3.
b^(n-1) mod n = 1.
23609 is prime.
b^((n-1)/23609)-1 mod n = 27458299228746, which is a unit, inverse 10679667100567.
1433 is prime.
b^((n-1)/1433)-1 mod n = 13658565625703, which is a unit, inverse 104633227636071.
(1433 * 23609) divides n-1.
(1433 * 23609)^2 > n.
n is prime by Pocklington's theorem.