Primality proof for n = 6473:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=809.html>809 is prime.</a>
<br>b^((n-1)/809)-1 mod n = 255, which is a unit, inverse 330.
<p>(809) divides n-1.
<p>(809)^2 > n.
<p>n is prime by Pocklington's theorem.