Perfect numbers

A perfect number is a number which is equal to the sum of its factors, including 1 but not the number itself.

This page is an exercise in using web workers to perform calculations in the background.

It takes a fraction of a second to find the first 4 perfect numbers, and roughly 8 mins to find the 5th (depending on browser, processor speed and load, etc); the script has yet to come up with the 6th perfect number despite exciting millions of electrons for well over an hour.