You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named N-[(E)-3-(4-bromophenyl)prop-2-enyl]-3-isoquinolin-5-ylsulfonylpropan-1-amine by IUPAC nomenclature, provide its molecular formula.
user
C21H21BrN2O2S
assistant