Math
Prime Number Calculator
Check whether a whole number is prime, composite, or neither.
Formula
A prime number has exactly two divisors, 1 and itself. A number above 1 that has another divisor is composite.
How it works
Enter a whole number. The calculator tests divisors up to the square root. For example, 29 is prime, while 28 is composite.
FAQs
What does the Prime Number do?
It takes the values you enter and works out the prime number for you, showing the result straight away.
What should I enter?
Enter ordinary numbers in the boxes above. If a value does not make sense for this calculation, the page will ask you to check it instead of showing a wrong answer.
Can I use the result for homework or everyday maths?
Yes. It is a general-purpose maths helper; for exam or professional work, still check the steps against your own working.