You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-(3,3-dimethyl-2-oxobutyl)sulfanyl-6-ethyl-3-(3-methoxyphenyl)-5-methylthieno[2,3-d]pyrimidin-4-one by IUPAC nomenclature, provide its molecular formula.
user
C22H26N2O3S2
assistant