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How to find prime factors
Provide a whole number and divide it into prime values until no composite factor remains.
Enter a whole number
Type a safe integer whose absolute value is at least 2; negative values retain a −1 factor.
Run the factorisation
The calculator repeatedly tests prime divisors and records each exact division.
Check the product
Read the multiplication chain and confirm that multiplying the listed factors returns the original number.
Frequently Asked Questions
What is a prime factor?
A prime factor is a prime number that divides the original number exactly.
Can I factor a negative number?
Yes. The result includes −1 followed by the prime factors of its absolute value.
Is 1 a prime number?
No. Prime numbers have exactly two positive divisors, so 1 is neither prime nor composite.
What is the smallest prime factor?
For an even number it is 2; otherwise the calculator tests subsequent possible divisors.
Can I enter a decimal?
No. Prime factorisation is defined here for safe whole numbers only.
What is a composite number?
A composite number has more than two positive divisors and can be split into prime factors.
Why must the absolute value be at least 2?
Numbers −1, 0, and 1 do not have a standard prime factorisation.