unsigned long long int

ulli.c

#include <stdio.h>
#include <limits.h>

int main() {
  unsigned long long ulli;
  printf("%d", sizeof(ulli));
  printf("%llu\n", ULLONG_MAX);
  printf("%llu ... or \n", ~(unsigned long long)0);
  printf("%llu\n", (unsigned long long)0 - 1);
  return 0;
}