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 N-(2,6-diethylphenyl)-3-(5,6-dimethyl-4-oxothieno[2,3-d]pyrimidin-3-yl)propanamide is given. What is its corresponding molecular formula?
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C21H25N3O2S
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