Primality proof for n = 272333:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=661.html>661 is prime.</a>
<br>b^((n-1)/661)-1 mod n = 150860, which is a unit, inverse 194137.
<p>(661) divides n-1.
<p>(661)^2 > n.
<p>n is prime by Pocklington's theorem.