Math · FREE ONLINE TOOL

Factor Calculator

List the positive factors of an integer and its prime decomposition, with inputs capped to keep trial division responsive.

Your inputs

Calculations run in your browser. No account needed.

EXAMPLE RESULTCalculated locally
Factors
1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120, 180, 360
Factor count
24
Clear inputs. Transparent methods.
My workspace

Calculate with your inputs to save a result or compare scenarios.

How it works

A useful distinction

Square factors meet in the middle

Factors of 36 pair as 1×36, 2×18, 3×12, 4×9 and 6×6. The square-root factor appears only once in the list, which explains why perfect squares have an odd number of positive factors.

Understanding factors and prime factorization

A factor divides an integer without leaving a remainder. The factor list and the prime decomposition describe the same integer in different ways: one lists divisors, while the other expresses a product of prime numbers. Check how signs and special inputs are treated in the mode's notes. Multiplying the prime factors back together is a useful way to verify a decomposition.

Integer factorization: formula and assumptions

Test integer divisors up to √n, then divide repeatedly to obtain prime factors.

The input is limited to one trillion to keep trial division responsive.

Worked example

Using the Integer factorization example:

Inputs
Positive integer
360
Method

Test integer divisors up to √n, then divide repeatedly to obtain prime factors.

Result

Example result

Factors: 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120, 180, 360

Factor count: 24

These are illustrative inputs. Change the values to explore a different scenario.

Formula references

References explain the underlying methods; they do not imply endorsement or individual professional review of Finflo.

Common questions

What is the difference between factors and prime factors?

Factors divide the number without a remainder. Prime factors are prime numbers whose repeated product reconstructs it.

Why is the input limited to one trillion?

This implementation uses bounded trial division. The limit keeps the calculation responsive rather than implying that larger integers lack factors.

Prepared by Finflo. See our methodology and editorial policy.