Free online prime number checker and prime factorization tool. Check if any number is prime, find all factors, and get step-by-step prime factorization. Pure frontend, no server upload.
A prime number is a positive integer greater than 1 that has exactly two factors: 1 and itself. Examples: 2, 3, 5, 7, 11, 13.
Prime factorization breaks a composite number into its prime factors. For example, 12 = 2 Γ 2 Γ 3. Every number has a unique prime factorization.
The largest known prime is a Mersenne prime with millions of digits. For practical purposes, this tool checks numbers up to 999,999,999 efficiently.
1 has only one factor (itself), so it doesn't meet the definition of having exactly two factors. Primes must have exactly two distinct factors.
The test uses optimized trial division up to the square root of the number, checking divisibility by 2, 3, and then numbers of the form 6kΒ±1 for maximum efficiency.