Definition:Semiperfect Number

Definition
A semiperfect number is a positive integer which is equal to the sum of some or all of its (proper) divisors.

Also defined as
Some sources do not include the perfect numbers in the set of semiperfect numbers:


 * A semiperfect number is a positive integer which is equal to the sum of some, but not all of its (proper) divisors.

It is possible this is a mistake in, as the author of this page has not been able to corroborate this definition with any sources elsewhere.

Also known as
Some sources use a hyphen: semi-perfect number.

The term pseudoperfect is also often seen.

, possibly being jocular in his of $1997$, refers to such a number as pseudonymously pseudoperfect.