# composite number

A composite number is a positive integer which is not prime and not equal to 1. That is, $n$ is composite if $n=ab$, with $a$ and $b$ natural numbers both not equal to 1.

## Examples.

• 1 is not composite (and also not prime), by definition.

• 2 is not composite, as it is prime.

• 15 is composite, since $15=3\cdot 5$.

• 93555 is composite, since $93555=3^{5}\cdot 5\cdot 7\cdot 11$.

• 52223 is not composite, since it is prime.

More generally, we can define compositeness any time there is an ambient notion of an irreducible element . In an integral domain , for example, an element is said to be composite if it neither zero, a unit, nor irreducible.

Title composite number CompositeNumber 2013-03-22 12:39:37 2013-03-22 12:39:37 mathcam (2727) mathcam (2727) 9 mathcam (2727) Definition msc 11A41 composite
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