Problem 656. Calculate euler's phi function

Compute the euler's phi function of a large integer.

For more information about this topic please visit: https://en.wikipedia.org/wiki/Euler%27s_totient_function

With these constraints:

• n is a nonnegative integer greater than 0.
• "large integer" means 32bit integer
• vectorized Input

Examples:

1. eulerphi(4) = 2
2. eulerphi(11) = 10