對於一個大過2嘅奇數 k，一個正整數n係 k-hemiperfect數，若且唯若佢嘅除數函數σ(n))等於k/2 × n。
For an odd number k greater than 2, a positive integer n is a k-hemiperfect number, if and only if its divisor function σ(n)) is equal to k/2 × n.