Results for “what are prime number” · retrieved September 22, 2026

Quick answer

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself.

A prime number is a natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers. Equivalently, a prime number has exactly two distinct positive divisors: 1 and itself. Numbers greater than 1 that are not prime are called composite numbers. Primes are considered the fundamental building blocks of natural numbers because, according to the fundamental theorem of arithmetic, every natural number greater than 1 is either a prime itself or can be uniquely factorized into a product of primes.

Answer details

1

Definition by Divisors

A prime number must be greater than 1 and cannot be divided evenly by any natural number other than 1 and itself.

2

Composite Numbers

Any natural number greater than 1 that is not prime is classified as a composite number, meaning it can be formed by multiplying smaller natural numbers.

3

Fundamental Theorem of Arithmetic

The fundamental theorem of arithmetic states that every natural number greater than 1 is either a prime or can be uniquely represented as a product of prime numbers.

4

Why 1 is Not Prime

The number 1 is not considered prime because including it would violate the unique factorization property required by the fundamental theorem of arithmetic.

en.wikipedia.org

Prime number

A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways of writing it as a product, 1 × 5 or 5 × 1, involve 5 itself. However, 4 is composite because it is a product (2 × 2) in which both numbers are smaller than 4. Primes are central in number theory because of

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mathworld.wolfram.com

Prime Number -- from Wolfram MathWorld

Prime Number A prime number (or prime integer, often simply called a "prime" for short) is a positive integer that has no positive integer divisors other than 1 and itself. More concisely, a prime number is a positive integer having exactly one positive divisor other than 1, meaning it is a number that cannot be factored. For example, the only divisors of 13 are 1 and 13, making 13 a prime number, while the number 24 has divisors 1, 2, 3, 4, 6,

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britannica.com

Prime number

prime, any positive integer greater than 1 that is divisible only by itself and 1—e.g., 2, 3, 5, 7, 11, 13, 17, 19, 23, …....A key result of number theory, called the fundamental theorem of arithmetic(see arithmetic: fundamental theory), states that every positive integer greater than 1 can be expressed as the product of prime numbers in a unique fashion. Because of this, primes can be regarded as the multiplicative “building blocks” for the natu

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encyclopediaofmath.org

Prime number

Prime number 2020 Mathematics Subject Classification: Primary: 11A41 [MSN][ZBL] A natural number (positive integer) $ p > 1 $ that has only the two divisors 1 and $ p $. E.g., $$ 2 , 3 , 5 , 7 , 11 , 13 , 17 , 19 , 23 , 29 , 31 , . . . . $$...Natural numbers which are not prime are called composite. The concept of a prime number is fundamental in the study of divisibility of natural numbers. Thus, the fundamental theorem of elementary number th

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mathsisfun.com

Prime Numbers and Composite Numbers

A Prime Number is:...a whole number above 1 that can't be made by multiplying smaller whole numbers...Example: 5 is a prime number....We can't multiply smaller whole numbers (like 2, 3 or 4) to make 5...Any whole number greater than 1 is either Prime or Composite. See Fundamental Theorem of Arithmetic ....define a Prime Number using...When the only two factors of a number are 1 and the number, then it is a Prime Number...be Exactly Divided By

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khanacademy.org

Prime numbers (video)

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britannica.com

Prime numbers

Prime number The number 7 is a prime number, meaning it can be divided only by 1 and itself. (more)...A prime number is any number that can be divided only by 1 and itself. For example, 3 is a prime number because the only numbers that divide it are 1 and 3. The number 4 is not, because it can be divided by 1, 2, and 4. The prime numbers are sometimes called the chemical elements of the numbers, because any integer can be expressed as a product o

June 13, 2025

math.libretexts.org

1.2: Definitions - Prime Numbers - Mathematics LibreTexts

Consider the definition of a prime number....Definition: Prime Number...A prime number is a positive integer, greater than \(1\), whose only factors are \(1\) and itself....You probably first heard this...in Middle School, if not earlier. It is a perfectly valid definition of what it means for an integer to be prime. In more advanced mathematics, it was found that it was necessary to define a notion of primality for objects other than integ

May 8, 2019

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