Last Updated
：2025/11/30
untouchable number
Noun
Japanese Meaning
数学において、任意の正の整数の固有約数（その数自身を除くすべての正の約数）の和として表現されない正の整数を指す。
（ plural ）
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(mathematics) A positive integer that cannot be expressed as the sum of all the proper divisors of any positive integer (including the untouchable number itself).
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untouchable number
Proving that a given integer is an untouchable number often requires checking that no positive integer has its proper divisors summing to that integer.
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Proving that a given integer is an untouchable number often requires checking that no positive integer has its proper divisors summing to that integer.
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