What is a prime number?
- A natural number greater than 1 that has no positive divisors other than 1 and itself
- The first few primes: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, ...
- 2 is the only even prime number
- By convention, 0 and 1 are not considered prime
Fun prime facts
- Twin primes: pairs differing by 2 (3,5), (5,7), (11,13), (17,19)
- Mersenne primes: primes of form 2ⁿ−1 (3, 7, 31, 127, 8191, ...)
- Largest known prime (2024): 2^82,589,933 − 1 (about 24.8 million digits)
- Primes are essential to RSA encryption — your HTTPS connections rely on them