Primality proof for n = 28771:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=137.html>137 is prime.</a>
<br>b^((n-1)/137)-1 mod n = 18560, which is a unit, inverse 479.
<p><a href=7.html>7 is prime.</a>
<br>b^((n-1)/7)-1 mod n = 13823, which is a unit, inverse 13094.
<p>(7 * 137) divides n-1.
<p>(7 * 137)^2 > n.
<p>n is prime by Pocklington's theorem.