Korselt criterion
= Korselt criterion
{c}
A composite integer $N$ is Carmichael exactly when it is square-free and $p-1$ divides $N-1$ for every prime $p$ dividing $N$.
= Korselt criterion
{c}
A composite integer $N$ is Carmichael exactly when it is square-free and $p-1$ divides $N-1$ for every prime $p$ dividing $N$.