Prime Number Checker
? Frequently Asked Questions
What is a prime number?
A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. The first few primes are 2, 3, 5, 7, 11, 13. Note that 1 is NOT prime.
How does the checker determine primality?
The checker uses trial division for small numbers and more efficient algorithms like Miller-Rabin for larger numbers. It tests divisibility by potential factors up to the square root of the number.
What's the largest number it can check?
Most web-based checkers can reliably test numbers up to several million or billion. Very large numbers may take longer to check. For cryptographic primes (hundreds of digits), specialized tools are needed.
Is 1 considered a prime number?
No, 1 is not prime by modern mathematical definition. Prime numbers must have exactly two distinct divisors: 1 and themselves. Since 1 only has one divisor (itself), it's excluded.
Can it show the prime factors if not prime?
Yes! When a number isn't prime, many checkers show its prime factorization. For example, 12 = 2² × 3. This helps understand the number's structure and divisibility.
Is my data safe and secure?
Yes, absolutely! This tool runs entirely in your browser. All data processing happens locally on your device - nothing is uploaded to our servers. Your files and data never leave your computer, ensuring complete privacy and security.