47 (forty-seven) is the natural number following 46 and preceding 48. It is a prime number. It is the adopted favorite number of Pomona College, a liberal arts college in Southern California, whose alumni have added cultural references to it in numerous places, including many Star Trek episodes.

Mathematics

47 is a safe prime, an isolated prime, a highly cototient number, an Eisenstein prime, and a Lucas number. 47 is also a supersingular prime. It is the last consecutive prime number that divides the order of at least one sporadic group.

In science

47 is the atomic number of silver. After 47 years – 22 synodic periods of 780 days each – Mars returns to the same position among the stars and is in the same relationship to the Earth and Sun. The ancient Mesopotamians discovered this cycle.

In popular culture

Pomona College

Other

Late rapper Capital Steez was infatuated with the number 47 and what it meant spiritually. He believed the number 47 was the "perfect expression of balance in the world", representing the tension between the heart and the brain (the fourth and seventh chakras, respectively.) The number featured on the cover of AmeriKKKan Korruption, stylized to resemble a swastika.