composite number

Definitions

A (nonzero) natural number that is expressible as the product of two (or more) natural numbers other than itself and 1.

Equivalents

Examples

“It is evident, moreover, that if a composite number⟳ terminates in any one of the digits 1, 3, 7, 9, no one of its factors can be the number⟳ 5, or any number⟳ ending in 5.”

“The above remark⟳ applies also to many composite numbers which are not Carmichael numbers, but which are still not shown to be composite by Fermat's theorem for a specific base⟳ a.[…]Therefore, using Euler's criterion or a strong primality test⟳ with enough bases will finally reveal⟳ any composite number⟳ or, alternatively, prove⟳ the primality of any prime N.”

“It is interesting that in each interval composite numbers are one-to-one assigned to the comparable composite knots while prime numbers are one-to-one assigned to prime knots.”

CEFR level