# Definition:Prime Number/Also defined as

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## Definition

Some treatments of number theory define a **prime** as being either positive or negative, by specifying that a **prime number** is an integer with exactly $4$ integer divisors.

By this definition, a composite number is defined as an integer (positive or negative) which is not prime and not equal to $\pm 1$.

There are advantages to this approach, because then special provision does not need to be made for negative integers.

Some sources implement this notion by introducing the concept of a **prime integer**.

## Sources

- 1989: Ephraim J. Borowski and Jonathan M. Borwein:
*Dictionary of Mathematics*... (previous) ... (next):**prime number**or**prime**