You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-tert-butyl-N-[2-(3,4-difluoroanilino)-2-oxoethyl]-4,5-dimethylthieno[2,3-d]pyrimidine-6-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H22F2N4O2S
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