Primality proof for n = 4681609:
Take b = 2.
b^(n-1) mod n = 1.
2011 is prime.
b^((n-1)/2011)-1 mod n = 3706699, which is a unit, inverse 1506556.
97 is prime.
b^((n-1)/97)-1 mod n = 4185920, which is a unit, inverse 914856.
(97 * 2011) divides n-1.
(97 * 2011)^2 > n.
n is prime by Pocklington's theorem.