You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-O-ethyl 4-O-propan-2-yl 5-[[5-[(4-bromo-3-nitropyrazol-1-yl)methyl]furan-2-carbonyl]amino]-3-methylthiophene-2,4-dicarboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H21BrN4O8S
assistant