Too many cooks spoil the broth! (How would you express that idea in Swedish?)
here is says: tjugoen , is tjugoett also correct? or is there a reason to pick one over the other?
Stick to tjugoen, it sounds a lot more correct to a native. I honestly don't know why that is so, though. Hopefully someone more knowledgeable will tune in eventually and explain.
This is really interesting! First I thought that it's just because you say "en kock" so it makes sense to say "tjugoen kockar". But, it is actually "ett hus" and you still say "tjugoen hus".
I found a comment about this here. It basically says that "tjugoen", trettioen" etc never are declined.
The only exception is when you're talking about numbers, number of years or something like that. This means that you say "Han är tjugoett år" for example.
That was my first thought too ... tjugoen, if it is an en word, and tjugoett, if it is an ett word. Not the case apparently.