Prime Number Tools - Free Online Tool | PivaBox

Prime number toolkit — check primality, find factors, nearest primes, count primes in range

How to Use Prime Number Tools

1. Enter a number in the input field and select an operation tab: Check Primality to test if it's prime, Prime Factorization to break it down into prime factors, or Next/Previous Prime to find nearby primes
2. For Primes in Range, enter a start and end value to generate all prime numbers within that interval. For Prime Pi, enter n to see how many primes exist up to n
3. Click Generate or press Enter to see results. The factorization tab animates each division step-by-step to help you understand the process

Frequently Asked Questions

Is this prime number tool free?

Yes, PivaBox Prime Number Tools is completely free. All primality tests and factorizations run locally in your browser — no data is uploaded to any server.

How large a number can I test?

The tool supports numbers up to 1,000,000 for primality testing and prime counting. Prime factorization works for any integer up to JavaScript's safe integer limit (9,007,199,254,740,991), though larger numbers may take longer to factor.

How does the primality test work?

It uses trial division up to the square root of n with a 6k±1 optimization. For n < 2: not prime. Divisible by 2 or 3: not prime. Then check divisors of the form 6k±1 up to √n. If no divisor is found, the number is prime.