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 2-[[4-(5-bromo-3-methylpyridin-2-yl)-4-hydroxybutyl]amino]-5-[(6-methyl-1-oxidopyridin-1-ium-3-yl)methyl]-1H-pyrimidin-6-one is given. What is its corresponding molecular formula?
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C21H24BrN5O3
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