Thread: Carmichael number

Show that 1729 is a Carmichael number.

Originally Posted by aaronrj

Show that 1729 is a Carmichael number.

Theorem (Korselt 1899): A positive composite integer n is a Carmichael number if and only if n is square-free, and for all prime divisors p of n, it is true that p − 1 | n − 1

1729=7x13x19

See this.