Primality proof for n = 1948699:
Take b = 2.
b^(n-1) mod n = 1.
523 is prime.
b^((n-1)/523)-1 mod n = 114069, which is a unit, inverse 994397.
23 is prime.
b^((n-1)/23)-1 mod n = 1034814, which is a unit, inverse 593413.
(23 * 523) divides n-1.
(23 * 523)^2 > n.
n is prime by Pocklington's theorem.