Unitary Multiperfect Number

A number $n$ which is an Integer multiple $k$ of the Sum of its Unitary Divisors $\sigma^*(n)$ is called a unitary $k$-multiperfect number. There are no Odd unitary multiperfect numbers.

References

Guy, R. K. ``Unitary Perfect Numbers.'' §B3 in Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, pp. 53-59, 1994.