Primality proof for n = 203333173:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=2420633.html>2420633 is prime.</a>
<br>b^((n-1)/2420633)-1 mod n = 125851850, which is a unit, inverse 113605773.
<p>(2420633) divides n-1.
<p>(2420633)^2 > n.
<p>n is prime by Pocklington's theorem.