How many numbers n less than 100 have exactly one divisor other than 1 and n?

How many positive integers less than 2000 are of the form x^n for some positive integer x and n\ge 2?

Thank you so much if you answered!

Imnotamaster Sep 17, 2019

#1**+3 **

How many numbers n less than 100 have exactly one divisor other than 1 and n?

n divsors

4 1 2 4

9 1 3 9

25 1 5 25

49 1 7 49

CPhill Sep 17, 2019

#4**+2 **

Notice Cphill's answers

they are ODD perfect squares except for 4, and ONLY prefect squares.

Answers like 81 won't work because it is a perfect power of 4 and 64 is a perfect cube.

CalculatorUser Sep 17, 2019