🧩 Factor Calculator
Factors are the integers that divide a number evenly — the complete factor list of 12 is 1, 2, 3, 4, 6, 12. Finding them by trial division up to the square root is fast and always complete.
Enter a positive integer (up to one billion). You get every factor in order, how many there are, and a prime check: a number with exactly two factors is prime.
How to use this calculator
Type a positive integer and press Calculate to list every factor.
- Type a positive integer into the Integer field, up to one billion.
- Press Calculate.
- Read the complete factor list as the headline result.
- Check the factor count and the prime verdict underneath.
Frequently asked questions
What does this factor calculator list?
Every positive integer that divides your number evenly, in ascending order. The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18 and 36.
How does it test for prime numbers?
A prime number has exactly two factors: 1 and itself. If the factor count is 2, the calculator reports the number as prime, as with 13 giving 1 and 13.
What is the largest number it accepts?
One billion (1,000,000,000). Trial division up to the square root keeps even large inputs fast, but beyond that the wait grows too long for a browser.
Why stop at the square root?
Factors come in pairs multiplying to the number, and one factor of each pair is always at or below the square root. Checking up to that point finds every pair with no wasted work.