You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[2-[5-iodo-3-(3-sulfopropyl)-1,3-benzothiazol-3-ium-2-yl]-2H-1,3-benzothiazol-3-yl]propane-1-sulfonic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H22IN2O6S4+
assistant