85 (number)
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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.[1]
- with a prime aliquot sum of 23 in the short aliquot sequence (85,23,1,0).
- an octahedral number.[2]
- a centered triangular number.[3]
- a centered square number.[4]
- a decagonal number.[5]
- 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.[6]
- the length of the hypotenuse of four Pythagorean triangles.
- a Smith number in decimal.[7]
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".
References
External links
- 85
- Jorge Stolfi, The Hollywood Constant.
- ↑ Template:Cite OEIS
- ↑ Template:Cite OEIS
- ↑ Template:Cite OEIS
- ↑ Template:Cite OEIS
- ↑ Template:Cite OEIS
- ↑ 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.
- ↑ Template:Cite OEIS