Primality proof for n = 15698303:
Take b = 2.
b^(n-1) mod n = 1.
29179 is prime. b^((n-1)/29179)-1 mod n = 690112, which is a unit, inverse 276632.
(29179) divides n-1.
(29179)^2 > n.
n is prime by Pocklington's theorem.