You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl (6R)-6-[3-(3,3-dimethylbutanoylamino)phenyl]-3,4-dimethyl-2-sulfanylidene-1,6-dihydropyrimidine-5-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H29N3O3S
assistant