Primality proof for n = 267983539294927:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=490812343031.html>490812343031 is prime.</a>
<br>b^((n-1)/490812343031)-1 mod n = 168666067834047, which is a unit, inverse 72442089171299.
<p>(490812343031) divides n-1.
<p>(490812343031)^2 > n.
<p>n is prime by Pocklington's theorem.