Mathematics & StatisticsLast updated: 2026-10-27

Prime Factorization

Factor an integer at least 2 with up to 15 digits. Check product and exponent forms, positive divisor count and primality. Press Factorize or Enter to run.

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Enter an integer and press Factorize.

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How to use

  1. 1

    Enter a number

    Type an integer at least 2 with up to 15 digits, then press Factorize or Enter (e.g. 360).

  2. 2

    Read the factors

    The product form (2×2×2×3×3×5) and exponent form (2³×3²×5) are shown.

  3. 3

    Check the divisors too

    The number of divisors and whether the number is prime are displayed as well.

Features

  • Shown in both product and exponent form
  • Divisor count and prime check included
  • Supports integers up to 15 digits (trial division)
  • Everything computed in your browser; nothing is transmitted

Use cases

Checking homework

Verify factorization answers, including the exponent form.

Counting divisors

Use the exponents to confirm the number of divisors.

GCD and LCM preparation

Compare the factors of two numbers to find common primes for the GCD.

Details

Prime factorization means writing a positive integer as a product of prime numbers only. For example, 360 = 2×2×2×3×3×5, or 2³×3²×5 in exponent form. Every integer greater than 1 has exactly one prime factorization (the fundamental theorem of arithmetic).

Trial division of 360 gives three factors of 2, two of 3 and one of 5. Tests need only reach the square root of the remaining quotient, but large primes can require more trials. The 15-digit input limit is not a speed guarantee.

Prime factorization underlies greatest common divisors, least common multiples and counting divisors. It also underpins security: the difficulty of recovering two large primes from their product is the foundation of RSA encryption. Everything runs in your browser and nothing you enter is transmitted.

FAQ

Can 1 be factored?

1 has no prime factors and this tool starts at 2. The prime 2 is displayed as itself.

How is a prime number detected?

A number above 1 whose only divisors are 1 and itself is shown as prime. If the input itself is prime, that is displayed directly.

How is the number of divisors calculated?

Add 1 to each exponent and multiply: 360 = 2³×3²×5 gives (3+1)×(2+1)×(1+1) = 24 divisors.

How large a number can I enter?

From 2 to 999,999,999,999,999. Even within 15 digits, processing time depends on factor sizes. Editing clears the old result; press Factorize or Enter to run again.

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Verified: Factorization, exponent form, divisor count, prime detection and error states are covered by browser tests

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