Keith number

In mathematics a trimorphic number is a number whose cube ends in the number itself. For example, 4³ = 64, 24³ = 13824, and 249³ = 15438249.

The first few trimorphic numbers are:

1, 4, 5, 6, 9, 24, 25, 49, 51, 75, 76, 99, 125, 249 ... (sequence A033819 in OEIS)

Every automorphic number is also a trimorphic number, but there are trimorphic numbers which are not automorphic (such as 4, 9 and 24).

References

Eric W. Weisstein, Trimorphic Number at MathWorld.