You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(Z)-3-[(2-chlorophenyl)methylamino]-2-cyano-N-[2-(3,4-dimethoxyphenyl)ethyl]prop-2-enamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H22ClN3O3
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