You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-(2-chlorophenyl)-2-[3-[(4-fluorophenyl)methyl]-2,4-dioxothieno[3,2-d]pyrimidin-1-yl]acetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H15ClFN3O3S
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