You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(3-bromophenyl)-3-[(6-ethyl-2-pyrrol-1-yl-5,7-dihydro-4H-thieno[2,3-c]pyridin-3-yl)methyl]urea The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H23BrN4OS
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