Primality proof for n = 6945557:
Take b = 2.
b^(n-1) mod n = 1.
1736389 is prime. b^((n-1)/1736389)-1 mod n = 15, which is a unit, inverse 3241260.
(1736389) divides n-1.
(1736389)^2 > n.
n is prime by Pocklington's theorem.