[mattashii]

If you're going that way, you can also interpret it - pardon my programming - as the following:

  int result; 
  for (int i = 0; i < 77232917; i++) { 
      result = 2 * 2; 
  } 
  return result - 1; 

... which obviously results in 3. Also a (mersienne) prime, but not quite as big as you'd expect, and certainly not millions of digits long.

[nopacience]

  int result; 
  for (int i = 0; i < 77232917; i++) { 
      result = 2 * 2; <----- you basically said result=4 77232917 times 
  } 
  return result - 1; <--- and then 4-1=3

so of course it will always be 3

[colanderman]

That is the joke.

[teilo]

Yeah, I suppose if one wants to be pedantic. But we know what it means.