Composite number

A composite number is a positive integer that can be factored as a product of two or more prime numbers. Every integer greater than one is either a prime number or a composite number. The number one is considered to be neither prime nor composite. The integer 14 is a composite number because it can be factored as 2 × 7.

Properties

All even numbers greater than 2 are composite numbers.
All composite numbers are non-primes.
The smallest composite number is 4.
One has $(n-1)! + 1\,\,\, \not\equiv \,\, 0 \pmod{n}$ for all composite numbers $n\,\!$ greater than 4 (Wilson's theorem).
Also, $(n-1)! \,\,\, \equiv \,\, 0 \pmod{n}$ for all composite numbers $n\,\!$ greater than 4 (composite theorem).

Composite number

Properties

See also: Composite number, 14 (number), 1 (number), 2 (number), 7 (number), Composite theorem, Integer, Negative and non-negative numbers, Prime number, Wilson's theorem