An Achilles number is a positive integer that is powerful (in the sense that each prime factor occurs with exponent greater than one) but imperfect (in the sense that the number is not a perfect power). The first few are 72, 108, 200, 288, 392, 432, ... (OEIS A052486).
Achilles Number
See also
Perfect Power, Powerful NumberExplore with Wolfram|Alpha
References
Sloane, N. J. A. Sequence A052486 in "The On-Line Encyclopedia of Integer Sequences."Referenced on Wolfram|Alpha
Achilles NumberCite this as:
Weisstein, Eric W. "Achilles Number." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/AchillesNumber.html