You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(5Z)-5-(3-ethyl-5-methoxy-1,3-benzothiazol-2-ylidene)-3-(2-phenylethyl)-2-sulfanylidene-1,3-thiazolidin-4-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H20N2O2S3
assistant