Number

Prime number

A whole number greater than 1 whose only factors are 1 and itself.

Definition

The first primes are 2, 3, 5, 7, 11, 13, 17, 19, 23. 1 is NOT a prime. 2 is the only even prime. Every other prime is odd.

Common confusion

Students often include 1 as prime. By the modern definition, 1 is not prime.

Used in these topics

Related terms

Factor

A number that divides another exactly, with no remainder.

Integer

A whole number — positive, negative or zero. No fractions or decimals.

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