Semiperfect number
![Demonstration, with Cuisenaire rods, of the perfection of the number 6](/Images/godic/202502/10/Perfect_number_Cuisenaire_rods_63112.png")
![](/Images/godic/202502/10/Lattice_of_the_divisibility_of_60.svg3113.png")
In number theory, a semiperfect number or pseudoperfect number is a natural number n that is equal to the sum of all or some of its proper divisors. A semiperfect number that is equal to the sum of all its proper divisors is a perfect number.
The first few semiperfect numbers are