Break an integer down into prime factors

With Prime factors, students, teachers and analysts can verify a calculation during study or analysis. Break an integer down into prime factors.

Break an integer down into prime factors. The tool is free in your browser and shows the result without asking you to create an account.

How to use

Enter the integer you want to break down; the value must sit between 2 and 1,000,000,000.
Run the operation and the prime factors of that number are listed for you.
Multiply the factors back together, by hand or with a calculator, to rebuild your starting number.
Clear the box and repeat the operation whenever you have another value to study.

Example

The sample breaks down 360. After running it, take the factors shown and multiply them back together to confirm that they rebuild 360. That quick check catches most transcription mistakes before you reuse the list.

Input

Output

2 × 2 × 2 × 3 × 3 × 5

Limits and formats

Only whole numbers between 2 and 1,000,000,000 are handled.
If the number is prime, the breakdown simply returns the number itself; that is expected, not a glitch.
Multiply the factors back together before copying the answer into homework or a report.
The page shows the factors but does not explain the method or the intermediate steps.

Where processing happens

The whole breakdown happens inside your browser, on the integer you have just entered. Nothing is exported outside and nothing stays in memory once you leave the page. You can therefore run as many attempts as you like.

Frequently asked questions

Why does a prime number come back unchanged?

A prime number has no divisor other than 1 and itself, so its factorisation is just that number. If you were expecting several factors, check that the value you typed is the one from your exercise.

What happens if I enter 1?

The accepted range starts at 2, because 1 has no useful prime factorisation. The field expects a value between 2 and 1,000,000,000, and anything outside that range falls outside what this page can answer.

What is a prime factorisation good for?

It helps you simplify a fraction, find a common multiple or confirm that a number is prime. It also shows which numbers multiply together to give yours, which makes a calculation easier to explain.