- Quasiperfect number
In

mathematics , a**quasiperfect number**is a theoreticalnatural number "n" for which the sum of all itsdivisor s (thedivisor function "σ"("n")) is equal to 2"n" + 1. Quasiperfect numbers areabundant number s.No quasiperfect numbers have been found so far, but if a quasiperfect number exists, it must be an odd

square number greater than 10^{38}and have at least seven distinctprime factor s. [*cite journal|author=Hagis, Peter & Cohen, Graeme L.,|title=Some results concerning quasiperfect numbers|journal=J. Austral. Math. Soc. Ser. A|volume=33|year=1982|pages=275–286*]**Notes****References***

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