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The tables below list all of the divisors of the numbers 1 to 1000. A divisor of an integer ''n'' is an integer ''m'', say, for which ''n''/''m'' is again an integer (which is necessarily also a divisor of ''n''). For example, 3 is a divisor of 21, since 21/3 = 7 (and 7 is also a divisor of 21). If ''m'' is a divisor of ''n'' then so is −''m''. The tables below only list positive divisors. == Key to the tables == *''d''(''n'') is the number of positive divisors of ''n'', including 1 and ''n'' itself *σ(''n'') is the sum of all the positive divisors of ''n'', including 1 and ''n'' itself *''s''(''n'') is the sum of the proper divisors of ''n'', which does not include ''n'' itself; that is, ''s''(''n'') = σ(''n'') − ''n'' *a perfect number equals the sum of its proper divisors; that is, ''s''(''n'') = ''n''; the only perfect numbers between 1 and 1000 are 6, 28 and 496 *amicable numbers and sociable numbers are numbers where the sum of their proper divisors form a cycle; the only examples below 1000 are 220 and 284 *a deficient number is greater than the sum of its proper divisors; that is, ''s''(''n'') < ''n'' *an abundant number is less than the sum of its proper divisors; that is, ''s''(''n'') > ''n'' *a prime number has only 1 and itself as divisors; that is, ''d''(''n'') = 2. Prime numbers are always deficient as ''s''(''n'')=1 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「Table of divisors」の詳細全文を読む スポンサード リンク
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