You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-(5-bromo-2-hydroxy-1-propan-2-ylindol-3-yl)imino-4-(2,4-dichlorophenoxy)butanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H20BrCl2N3O3
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