You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named 3-[2-[2-[4-(dimethylamino)phenyl]ethenyl]-5-methyl-1,3-benzothiazol-3-ium-3-yl]propane-1-sulfonic acid is given. What is its corresponding molecular formula?
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C21H25N2O3S2+
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