No, they go down all the way to 8, that's a 64' pipe. There are only very few organs in the world that can do this and I'm not even sure if those stops are functional.
I have a 'virtual' version of that here and you simply can't hear it (you can feel it though).
I heard they have pipes that big at the Liverpool cathedral, but they only use them when the Queen was there, as they are literally wrecking the cathedral.
I totally get why they would want to limit the use of that particular register. At that frequency you're putting standing waves in the structure of the cathedral that are long enough to put significant stresses on the masonry. I've played around a bit with a 32' stop in a church and that already had me worried about the stained glass and the more delicate bits of stone work. Half that at volume must be very impressive.
I don't think it is written into a piece (at least not one that I know of) but if you play the 32' pedal C and C# together you get a ~2 Hz beat frequency that is amazing to hear but probably didn't help the church building that I worked at. :)
Hehe, that's nasty :) Yes, of course, you can get all the sums and differences by going up and down that stop and keeping the lowest note pressed all the time. You probably end up giving the wind machine a nice work out too.
I have a 'virtual' version of that here and you simply can't hear it (you can feel it though).
See:
https://www.mixtuur.com/en/whats-the-longest-organ-pipe-in-t...