Perfect power

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A positive integer $n$ is a perfect power if there exist integers $m, k$ such that $k \geq 2$ and $n = m^k$. In particular, $n$ is said to be a perfect $k$th power. For example, $64 = 8^2 = 4^3 = 2^6$, so $64$ is a perfect $2$nd, $3$rd and $6$th power.

We restrict $k \geq 2$ only because "being a perfect $1$st power" is a meaningless property: every integer is a $1$st power of itself.

Perfect second powers are also known as perfect squares and perfect third powers are also known as perfect cubes. This is because the area of a square and the volume of a cube is equal to the second and third powers of a side length, respectively.