47 (number)

47 (forty-seven) is the natural number following 46 and preceding 48. It is a prime number.

Mathematics
Forty-seven is the fifteenth prime number, a safe prime, and the fourth isolated prime. 47 is the number of trees on 9 unlabeled nodes.

47 is the sixth highly cototient number, and the eighth Eisenstein prime with no imaginary part and real part of the form $$3n - 1$$.

47 is the ninth strictly non-palindromic number, following 19 and preceding 53.

47 is the largest member of the simplest Cunningham chain,



where each prime member is one more than twice the previous. 47 is equivalently the fifth Thabit number of the form $$3 \cdot 2^n - 1$$ for positive $$n$$, relating to the pair of amicable numbers ${2, 5, 11, 23, 47}$.

47 is the ninth Lucas number (and sixth Lucas prime), where it is also the fourth Keith number since its digits appear as successive terms earlier in the sequence of Lucas numbers: ${17296, 18416}$

47 is the thirteenth supersingular prime. It is the last consecutive prime number that divides the order of at least one sporadic group, in its case it divides the order of the two largest such (non-pariah) groups: $$\mathbb {M}$$ and $$\mathbb {B}$$.

47 is the largest consecutive prime in Manjul Bhargava's prime-universality criterion theorem representative of all prime numbers: ${2, 1, 3, 4, 7, 11, 18, 29, 47, ...}.$

The forty-seventh triangular number (1128) is the dimensional representation of the largest vertex operator algebra with central charge of twenty-four, $$D_{24}$$.

In science
47 is the atomic number of silver.

Astronomy
The 47-year cycle of Mars: 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.

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 sixth chakra, respectively.) The number featured on the cover of AmeriKKKan Korruption, stylized to resemble a swastika.