Perfect number calculator in C++

Perfect number calculator.cpp

#include <iostream>
#include <math.h>

#define u64 unsigned long long

bool is_perfect(u64 num){
  u64 sum = 0;
  for (u64 d = 1; d < num; d += 1) {
    if (num % d == 0) sum += d;
    if (sum > num) return false;
  }
  if (sum==num) return true;
  return false;
}

int main(void) {
  u64 to_check = 2;
  u64 i = 1;
  while (true){
    if (is_perfect(to_check)) {
      std::cout << i << ". " << to_check << " is a perfect number" << std::endl;
      to_check += pow(10, i++);
    }
    to_check += 2;
  }
  return EXIT_SUCCESS;
}