I have updated the test with the new figures that I got. Initially I only tested with Python 2 with math.pow. I have to say I am quite disappointed with the performance of Python 3 though and even using the built-in pow function, PHP 5.6 still is the fastest in this particular case.
PHP is no better, if you add an intval call it will add almost 4 seconds to the result! This is an extraordinary proof that being a little sloppy can cost you a lot when using interpreted scripting languages!
Also, I am thinking if and how much speed gain could one inject by not using OOP in PHP...