Composite number
A composite number is a positive integer that has at least one positive divisor other than one or the number itself. Any integer greater than one that is not a prime number is a composite number, while the number one is a unit; it is neither prime nor composite.
For example, the integer 14 is a composite number because it can be factored as 2 × 7. Likewise, the integers 2 and 3 are not composite numbers because each of them can only be divided by one and itself.
The composite numbers up to 150 are
Every composite number can be written as the product of two or more (not necessarily distinct) primes. For example, the composite number 299 can be written as 13 × 23, and the composite number 360 can be written as 23 × 32 × 5; furthermore, this representation is unique up to the order of the factors. This fact is called the fundamental theorem of arithmetic.
There are several known primality tests that can determine whether a number is prime or composite, without necessarily revealing the factorization of a composite input.