80

80 = 2⁴ x 5.

80 has a representation as a sum of two squares: 80 = 4² + 8².

80 is the smallest number with exactly seven representations as a sum of three distinct primes: 80 = 2 + 5 + 73 = 2 + 7 + 71 = 2 + 11 + 67 = 2 + 17 + 61 = 2 + 19 + 59 = 2 + 31 + 47 = 2 + 37 + 41.

80 is 2222 in base 3.

80 is the smallest number that is diminished by taking its sum of letters (writing out its English name and adding the letters using a = 1, b = 2, c = 3, . . .): EIGHTY = 5 + 9 + 7 + 8 + 20 + 25 = 74.

Around the World in Eighty Days is a novel by Jules Verne.

Source: Number Gossip