What Is?
A Prime number is a natural number greater than 1 that has exactly two distinct positive divisors: 1 and itself. The smallest prime number is 2, which is also the only even prime. All other even numbers are divisible by 2 and therefore composite.
Prime numbers form the fundamental building blocks of the natural numbers, since every integer greater than 1 can be expressed uniquely as a product of primes, a result known as the Fundamental Theorem of Arithmetic. There are infinitely many primes, a fact first proven by Euclid around 300 BC. Although primes appear irregularly among the integers, mathematicians have discovered many fascinating patterns and conjectures about their distribution.
Today, prime numbers play a critical role in modern cryptography, particularly in algorithms like RSA, where the difficulty of factoring large numbers into primes ensures secure communication.