You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(5Z)-3-[(6-chloro-1,3-benzodioxol-5-yl)methyl]-5-[(3,4,5-trimethoxyphenyl)methylidene]-1,3-thiazolidine-2,4-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H18ClNO7S
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