You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[(1,1-dihydroxy-1,4-thiazinan-4-yl)methyl]-2-methyl-6-phenylthieno[2,3-d]pyrimidine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H21N3O2S2
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