Education
Prime Number Checker
Enter any non-negative whole number to find out whether it is prime. If it is composite, the tool shows its prime factorization and full list of divisors using efficient trial division up to the square root. Works on large integers and runs entirely in your browser.
Examples
Input · Composite numbers show their full prime factorization.
84
Output
Not prime — 2^2 × 3 × 7
How to use Prime Number Checker
Type a number
Enter any non-negative whole number you want to check.
See the verdict
The tool instantly tells you whether it is prime, composite, or neither.
Inspect the factors
For composite numbers, view the prime factorization and full divisor list.
Why use this tool
Instant prime or composite verdict
Shows prime factorization for composites
Lists all divisors of the number
Efficient trial division handles large integers
Frequently asked questions
No. Zero and one are neither prime nor composite, and the tool labels them accordingly.
Any whole number up to JavaScript's safe integer limit (about 9 quadrillion) is supported via trial division.
Discussion
Share feedback or ask a question about this tool.
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