Primality proof for n = 24821:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=73.html>73 is prime.</a>
<br>b^((n-1)/73)-1 mod n = 9049, which is a unit, inverse 7203.
<p><a href=17.html>17 is prime.</a>
<br>b^((n-1)/17)-1 mod n = 11546, which is a unit, inverse 22682.
<p>(17 * 73) divides n-1.
<p>(17 * 73)^2 > n.
<p>n is prime by Pocklington's theorem.