Prime Number — A prime number (or a prime) is a natural number that has exactly two distinct natural number divisors: 1 and itself. The smallest prime numbers are: 2, 3, 5, 7, 11, 13, 17, 19, 23,... For over two thousand years no practical use could be deducted from the discovery of prime numbers. The emergence of PCs radically changed the hidden use of prime numbers, prime numbers play a vital role in cryptography. The entanglement shown in the picture is a set of prime numbers juxtaposed with a set of natural numbers.