You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 4,5-dimethyl-1-propan-2-ylpyrimidin-2-one;6-methylidene-9-propan-2-yl-1H-purin-2-amine;6-methylidene-9-propan-2-yl-1H-purine;4-methylidene-1-propan-2-ylpyrimidin-2-one;5-methyl-4-methylidene-1-propan-2-ylpyrimidin-2-one;6-methyl-9-propan-2-ylpurine;4-methyl-1-propan-2-ylpyrimidin-2-one by IUPAC nomenclature, provide its molecular formula.
user
C61H89N21O4
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