85 (number)

Template:Pp-pc 85 (eighty-five) is the natural number following 84 and preceding 86. Template:Infobox number

In mathematics

85 is:

• the product of two prime numbers (5 and 17), and is therefore a semiprime of the form (5.q) where q is prime.
• specifically, the 24th Semiprime, it being the fourth of the form (5.q).
• together with 86 and 87, forms the second cluster of three consecutive semiprimes; the first comprising 33, 34, 35.<ref>Template:Cite OEIS</ref>
• with a prime aliquot sum of 23 in the short aliquot sequence (85,23,1,0).
• an octahedral number.<ref>Template:Cite OEIS</ref>
• a centered triangular number.<ref>Template:Cite OEIS</ref>
• a centered square number.<ref>Template:Cite OEIS</ref>
• a decagonal number.<ref>Template:Cite OEIS</ref>
• 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.<ref>Template:Cite OEIS. The two smaller numbers on this list, 50 and 65, have 1 as one of the squares in their representations as sums of two squares.</ref>
• the length of the hypotenuse of four Pythagorean triangles.
• a Smith number in decimal.<ref>Template:Cite OEIS</ref>

In other fields

• The radix of the Ascii85 (sometimes called Base85) binary-to-text encoding
• Part of the assignation for the Toyota AE85, commonly referred to as an "eight-five".

External links

• 85
• Jorge Stolfi, The Hollywood Constant.