You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 8-ethyl-2-[4-[[(2R)-1-methoxy-3-methyl-1-oxobutan-2-yl]carbamothioyl]piperazin-1-yl]-5-oxopyrido[2,3-d]pyrimidine-6-carboxylate by IUPAC nomenclature, provide its molecular formula.
user
C21H27N6O5S-
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