Primality proof for n = 80491:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=2683.html>2683 is prime.</a>
<br>b^((n-1)/2683)-1 mod n = 72374, which is a unit, inverse 25961.
<p>(2683) divides n-1.
<p>(2683)^2 > n.
<p>n is prime by Pocklington's theorem.