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87 (number)
87 (eighty-seven) is the natural number following 86 and preceding 88. ==In mathematics== 87 is the twenty-sixth distinct semiprime and the eighth of the form (3.q). The aliquot sum of 87 is 33 within the aliquot sequence (87,33,15,9,4,3,1,0) 86 being the eighteenth composite number in the 3-aliquot tree. 87 is the sum of the squares of the first four primes. It is also the sum of the sum of divisors of the first ten integers.
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「87 (number)」の詳細全文を読む
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