In mathematics, a prime number is a positive integer greater than 1 that is not a product of two smaller positive integers. In other words, a prime number is a number that is divisible only by 1 and itself. For example, the number 13 is a prime number because it can only be divided by 1 and 13.
Prime numbers have a number of important properties. For example, they are used in cryptography to encrypt and decrypt messages. Prime numbers are also used to generate random numbers and in a variety of other applications. The study of prime numbers has a long history, dating back to the ancient Greeks. In the 3rd century BC, the Greek mathematician Euclid proved that there are an infinite number of prime numbers.