Primary pseudoperfect number

In mathematics, and particularly in number theory, N is a primary pseudoperfect number if it satisfies the Egyptian fraction equation 1 N + ∑ p | N 1 p = 1 , {\displaystyle {\frac {1}{N}}+\sum _{p\,|\;\! N}{\frac {1}{p}}=1,} where the sum is over only the prime divisors of N. == Properties == Equivalently, N is a primary pseudoperfect number if it satisfies 1 + ∑ p | N N p = N . {\displaystyle 1+\sum _{p\,|\;\!

Source: Wikipedia — Primary pseudoperfect number (CC BY-SA 4.0)