You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[4-[(E)-3-(6-nitro-1,3-benzodioxol-5-yl)prop-2-enoyl]piperazin-1-yl]sulfonylbenzonitrile is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H18N4O7S
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