- hyperperfect number
- мат.гиперсовершенное число
English-Russian scientific dictionary. 2008.
hyperperfect number
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Hyperperfect number — In mathematics, a k hyperperfect number (sometimes just called hyperperfect number ) is a natural number n for which the equality n = 1 + k ( σ ( n ) − n − 1) holds, where σ ( n ) is the divisor function (i.e., the sum of all positive divisors of … Wikipedia
1909 (number) — Number|number = 1909 range = cardinal = one thousand nine hundred [and] nine ordinal = th ordinal text = one thousand nine hundred [and] ninth numeral = factorization = 23 cdot 83 prime = divisor = 1, 23, 83, 1909 unicode = greek prefix = latin… … Wikipedia
Prime number — Prime redirects here. For other uses, see Prime (disambiguation). A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself. A natural number greater than 1 that is not a prime number is… … Wikipedia
Perfect number — In number theory, a perfect number is a positive integer that is equal to the sum of its proper positive divisors, that is, the sum of its positive divisors excluding the number itself (also known as its aliquot sum). Equivalently, a perfect… … Wikipedia
Highly composite number — This article is about numbers having many divisors. For numbers factorized only to powers of 2, 3, 5 and 7 (also named 7 smooth numbers), see Smooth number. A highly composite number (HCN) is a positive integer with more divisors than any… … Wikipedia
300 (number) — This article is about the numbers 300 to 399. For other uses of 300, see 300 (disambiguation). For the guitar, see Gibson ES 335. For the British tilting train, see British Rail Class 390. For the Dada magazine, see 391 (magazine). For the… … Wikipedia
List of recreational number theory topics — This is a list of recreational number theory topics (see number theory, recreational mathematics). Listing here is not pejorative: many famous topics in number theory have origins in challenging problems posed purely for their own sake. See list… … Wikipedia
Composite number — A composite number is a positive integer which has a positive divisor other than one or itself. In other words a composite number is any positive integer greater than one that is not a prime number. So, if n > 0 is an integer and… … Wikipedia
Multiply perfect number — In mathematics, a multiply perfect number (also called multiperfect number or pluperfect number) is a generalization of a perfect number. For a given natural number k, a number n is called k perfect (or k fold perfect) if and only if the sum of… … Wikipedia
Deficient number — In number theory, a deficient number or defective number is a number n for which the sum of divisors σ(n)<2n, or, equivalently, the sum of proper divisors (or aliquot sum) s(n)<n. The value 2n − σ(n) (or n − s(n)) is… … Wikipedia
Harmonic divisor number — This article is about harmonic divisor numbers. For meanings of harmonic number, see harmonic number (disambiguation). In mathematics, a harmonic divisor number, or Ore number (named after Øystein Ore who defined it in 1948), is a positive… … Wikipedia
