Prime Number Calculator
This prime number calculator will find if a number is prime or composite. If it is composite the calculator will also find all of the factors of the composite number. Factorization or decomposition of composite numbers can be done on the Factoring Calculator.
Test for a prime number for any integer, or whole number, less than 10,000,000,000,000 (less than 10 trillion or a maximum of 13 digits).
What is a Prime Number?
A prime number is any integer, or whole number, greater than 1 that is only divisible by 1 and itself. In other words, a prime number only has two factors, 1 and itself.
Is 2 a prime number? Yes, 2 is a prime number because it only has two factors, 1 and 2.
Is 17 a prime number? Yes, 17 is a prime number because it only has two factors, 1 and 17.
Is 51 a prime number? No, 51 is NOT a prime number because it has more than two factors. 51 is a composite number and can be factored by any of the following numbers: 1, 3, 17, 51.
For a list of the first 1000 prime numbers see our See 1000 Prime Numbers Table.
References and Further Reading
Weisstein, Eric W. "Prime Number." From MathWorld--A Wolfram Web Resource.
Caldwell, Chris K. The Prime Pages.