Primality proof for n = 28287053:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=7071763.html>7071763 is prime.</a>
<br>b^((n-1)/7071763)-1 mod n = 15, which is a unit, inverse 24515446.
<p>(7071763) divides n-1.
<p>(7071763)^2 > n.
<p>n is prime by Pocklington's theorem.