prime number

American  

noun

Mathematics.

1. a positive integer that is not divisible without remainder by any integer except itself and 1, with 1 often excluded.

   The integers 2, 3, 5, and 7 are prime numbers.

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prime number British  

noun

1. Sometimes shortened to: prime.  an integer that cannot be factorized into other integers but is only divisible by itself or 1, such as 2, 3, 5, 7, and 11 Compare composite number

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prime number Scientific  

1. A positive integer greater than 1 that can only be divided by itself and 1 without leaving a remainder. Examples of prime numbers are 7, 23, and 67.

2. Compare composite number

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prime number Cultural  

1. A number that cannot be divided evenly by any other number except itself and the number one; 1, 3, 5, 7, and 11 are prime numbers.

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Etymology

Origin of prime number

First recorded in 1585–95

Example Sentences

Six is a perfect number, and seven is a prime number, but only a glutton for punishment would put them together in front of a bunch of 13-year-olds.

From The Wall Street Journal • Oct. 14, 2025

“It’s like an entire alien species living underneath our feet and then some prime number years they come out to say hello.”

From Seattle Times • Apr. 1, 2024

Two is my favorite number, so it’s definitely my favorite prime number.

From Scientific American • Nov. 22, 2022

Sixty-one is a prime number, just as the Slate News Quiz is a prime example of good quizzing fun.

From Slate • Oct. 7, 2022

As we become fluent readers we file away in memory tens of thousands of common word pairs, such as horse race, hunt ducks, cotton clothing, fat people, prime number, old man, and data point.

From "The Sense of Style" by Steven Pinker