The totient of a square is a cube (noch nicht übersetzt)

Consider the number 50.
50² = 2500 = 2² × 5⁴, so φ(2500) = 2 × 4 × 5³ = 8 × 5³ = 2³ × 5³. ¹
So 2500 is a square and φ(2500) is a cube.

Find the sum of all numbers n, 1 < n < 10¹⁰ such that φ(n²) is a cube.

¹ φ denotes Euler's totient function.