Implement this method:

public static int totient(int n) {

int count = 0;

for(int i = 1; i < n; i++)

if(gcd(n,i) == 1)

count++;

return count;

}

You can implement your own gcd(int a, int b) method, or find one of the many online.

This is exactly φ(21600) where φ is the Euler totient function. φ(21600) = 5760 That is, there are 5760 such numbers between 1 and 21600.

Euler introduced mathematical notation. He made contributions of complex analysis. He introduced the concept of a function, the use of exponential function, and logarithms in analytic proofs. Euler also produced the formula for the Riemann zeta function.

Yes, it is a property of homogeneous function.

Hermann Euler has written:

'Hermann Euler und Daisy Campi' -- subject(s): Exhibitions