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MATHEMATICAL MYSTERIES
We Know Only Three Wilson Primes
Every prime satisfies Wilson’s theorem. Only three known primes go one step further — and nobody knows if a fourth exists.
Prime numbers are already unusual. They become less frequent as numbers grow, resist simple patterns, and continue to generate questions that look elementary but remain unresolved.
Yet hidden among the primes is a far rarer species, the Wilson primes.
Only three are known:
What makes them special can be stated surprisingly simply.
For every prime p, Wilson’s theorem guarantees that (p − 1)! + 1 is divisible by p:
But Wilson primes satisfy a rarer condition: the same number is divisible by p²:






