You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 2-[3-(3,4-dihydro-2H-1,5-benzoxathiepin-3-ylamino)-2-methylpropyl]sulfanyl-6-ethylphenol into molecular formula.
user
C21H27NO2S2
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