@MartinBüttner I'd actually still bet on non-factoring-based approaches in most langs that have factoring. Specifically, try all reasonable root orders and take the largest one that gives a whole number.
What general tips do you have for golfing in D? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to D (e.g. "remove comments" is not an answer). Please post one tip per answer.
People call the bar at the end of the golf course the 19th hole (since golf courses have 18 holes). The byte part comes from the fact that we measure code size in bytes.