Prime Number Checker
Check if a number is prime instantly. Find all factors and understand prime number properties. Perfect for mathematics and number theory.
Prime Number Checker
How to Use This Checker
Enter any positive integer and click “Check Prime”. The calculator will determine if it’s prime, show all factors, and classify the number type. Prime numbers have exactly two factors: 1 and themselves.
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. For example, 2, 3, 5, 7, 11, 13 are prime. The number 1 is not considered prime. Prime numbers are the building blocks of all natural numbers.
Composite Numbers
Composite numbers have more than two factors. For example, 12 is composite because it has factors 1, 2, 3, 4, 6, and 12. Every composite number can be expressed as a product of prime numbers (prime factorization).
Properties of Prime Numbers
2 is the only even prime number. All other primes are odd. There are infinitely many prime numbers (proved by Euclid). The distribution of primes becomes less dense as numbers get larger, but never stops completely.
Applications of Prime Numbers
Prime numbers are crucial in cryptography (RSA encryption), computer science (hash tables), mathematics (number theory), and security systems. They’re used to create unbreakable codes and secure online transactions.
Frequently Asked Questions
Q: Is 1 prime? A: No, by definition primes must have exactly two factors. Q: Is 2 prime? A: Yes, it’s the only even prime. Q: Largest known prime? A: Currently over 24 million digits! Q: How to find primes? A: Use algorithms like Sieve of Eratosthenes.