63 (number)

63 is:

• a deficient composite number

• a highly cototient number.[1]
• a number of the form 2ⁿ − 1 (with n = 6), but it is not a Mersenne prime since n is not prime and 63 is certainly not prime either. It is the only number in the Mersenne sequence whose prime factors are each factors of at least one previous element of the sequence.
• a Woodall number i.e. of the form 2ⁿn − 1 with n = 4.[2]
• the third Delannoy number.[3]
• the sum of the powers of 2 from 0 to 5.
• palindromic and a repdigit in bases 2 (111111₂), 4 (333₄), 8 (77₈), 20 (33₂₀) and 62 (11₆₂).
• a centered octahedral number.[4]
• there are 63 posets with 5 unlabeled elements.[5]
• a Harshad number.

• The atomic number of europium.

Sixty-three is also:

• The code for international direct dial calls to the Philippines
• The hull number of the U.S. Navy's aircraft carrier USS Kitty Hawk (CV-63) and the USS Missouri (BB-63)
• The number of the French department Puy-de-Dôme
• The number of groats in a guinea in British pre-decimal currency
• A card game, popular in Carleton County, New Brunswick
• The Stoner 63, a machine gun
• The number of chromosomes found in the offspring of a donkey and a horse
• Class of '63 was a TV movie starring James Brolin (1973)

• There are 63 Tractates in the Mishna, the compilation of Jewish Law.
• There are 63 Saints (popularly known as Nayanmars) in South Indian Shaivism, particularly in Tamil Nadu, India.
• There are 63 Salakapurusas (great beings) in Jain cosmology.