Question

The integer 2821 is a Carmichael number.

(a) True

(b) False

This question was posed to me in an international level competition.

This interesting question is from Applications of Number Theory topic in section Number Theory and Cryptography of Discrete Mathematics

Answer 1

The correct option is (a) True

For explanation: By using the Fermat’s theorem, it follows that b^2820 is congruent to 1 (mod 2821).