By number of distinct colors, what official LEGO set has the most pieces?
I have a few:


3 colors: 2882 parts for 3450 
6/5 colors: 4502 parts for
40179. Note: color count depends if you include brick separator
as a part or not.
11 colors: 2428 parts for 10181
15 colors: 2455 parts for 2000431
23 colors: 7513 for 75192
37 colors: 2613 parts for 2000430