| 词条 | 8128 (number) |
| 释义 |
| number = 8128 | divisor = 1, 2, 4, 8, 16, 32, 64, 127, 254, 508, 1016, 2032, 4064 }} 8128 is the integer following 8127 and preceding 8129. It is most notable for being a perfect number, and one of the earliest numbers to be recognized as such. As a perfect number, it is tied to the Mersenne prime 127, 27 – 1, with 26 (27 – 1) yielding 8128. Also related to its being a perfect number, 8128 is a harmonic divisor number.[1] Another consequence of 8128 being a perfect number is that it has the same prime factors as the sum of its divisors, its cototient is a power of two, and it is a harmonic seed number (though there are deficient and abundant numbers that share these properties). 8128 is the 127th triangular number, the 64th hexagonal number, a happy number, the eighth 292-gonal number, and the fourth 1356-gonal number, as well as the 43rd centered nonagonal number.[2] See also
References1. ^{{cite web|title=Sloane's A001599 : Harmonic or Ore numbers|url=https://oeis.org/A001599|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|accessdate=2016-06-03}} {{DEFAULTSORT:8128 (Number)}}2. ^{{cite web|title=Sloane's A060544 : Centered 9-gonal (also known as nonagonal or enneagonal) numbers|url=https://oeis.org/A060544|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|accessdate=2016-06-03}} 1 : Integers |
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