85 (number)

In mathematics

• the product of two prime numbers, and is therefore a semiprime of the form where q is prime.
• specifically, the 24th Semiprime, it being the fourth of the form.
• together with 86 and 87, forms the second cluster of three consecutive semiprimes; the first comprising 33, 34, 35.
• with a prime aliquot sum of 23 in the short aliquot sequence.
• an octahedral number.
• a centered triangular number.
• a centered square number.
• a decagonal number.
• the smallest number that can be expressed as a sum of two squares, with all squares greater than 1, in two ways, 85 = 9² + 2² = 7² + 6².
• the length of the hypotenuse of four Pythagorean triangles.
• a Smith number in decimal.

  In other fields

• The radix of the Ascii85 binary-to-text encoding
• Part of the assignation for the Toyota AE85, commonly referred to as an "eight-five".