Primality proof for n = 1866869:
<p>Take b = 2.
<p>b^(n-1) mod n = 1.
<p><a href=466717.html>466717 is prime.</a>
<br>b^((n-1)/466717)-1 mod n = 15, which is a unit, inverse 124458.
<p>(466717) divides n-1.
<p>(466717)^2 > n.
<p>n is prime by Pocklington's theorem.