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86 (eighty-six) is the natural number following 85 and preceding 87. ==In mathematics== 86 is the 25th distinct semiprime and the 13th of the form (2.q). The aliquot sum of 86 is 46 within the aliquot sequence (86,46,26,16,15,9,4,3,1,0) 86 being the 17th composite number in the 3-aliquot tree. 86 is the middle number in the second cluster of three discrete semiprimes between 85 and 87 being themselves discrete semiprimes. 86 is a semiprime, nontotient and a noncototient. It appears in the Padovan sequence, preceded by the terms 37, 49, 65 (it is the sum of the first two of these). Since it is possible to find sequences of 86 consecutive integers such that each inner member shares a factor with either the first or the last member, 86 is an Erdős–Woods number. In base 10, it is a happy number and a self number. It is conjectured that 86 is the largest n for which the decimal expansion of 2n contains no 0. 86 is a repdigit in base 6 (222). 86 = (8 x 6 = 48) + (4 x 8 = 32) + (3 x 2 = 6). That is, 86 is equal to the sum of the numbers formed in calculating its multiplicative persistence. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「86 (number)」の詳細全文を読む スポンサード リンク
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