Primality proof for n = 49645261:
Take b = 2.
b^(n-1) mod n = 1.
41 is prime.
b^((n-1)/41)-1 mod n = 21966832, which is a unit, inverse 6825436.
31 is prime.
b^((n-1)/31)-1 mod n = 22206688, which is a unit, inverse 41093098.
(31^2 * 41) divides n-1.
(31^2 * 41)^2 > n.
n is prime by Pocklington's theorem.