What do you mean by "run on python"? Those companies use pretty much every language in existence (not quite, but you get the point, I hope).
Or take Google for example, where Python was (still is for all I know) one of the few officially sanctioned languages: Python, C++, Java (and now Go too -- which, contrary to popular belief hasn't been some kind of exclusive language Google uses, nor has it toppled C++/Java/Python etc from their codebases).
Another big elephant is OpenStack.