About the Prime Number Checker
The Prime Checker handles small cases directly and tests possible factors using a 6k +/- 1 loop up to the square root. When a divisor is found, the matching factor pair is displayed.
How to use the Prime Number Checker
- Enter a non-negative whole number within JavaScript's safe integer range.
- Run the divisibility test.
- Read prime status or the first discovered factor pair.
Practical tips
- One is neither prime nor composite.
- Trial division is best for moderate values, not cryptographic-size primes.