Carmichael Number has 3 Odd Prime Factors

From ProofWiki
Jump to navigation Jump to search


Let $n$ be a Carmichael number.

Then $n$ has at least $3$ distinct odd prime factors.


Historical Note

Robert Daniel Carmichael proved that a Carmichael Number has at least 3 distinct odd prime factors in $1912$, at around the same time that he discovered that $561$ was the smallest one.