You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 4-[4-(4-bromophenyl)sulfonylpiperazin-1-yl]-6-imidazol-1-yl-2-methylpyrimidine by IUPAC nomenclature, provide its molecular formula.
user
C18H19BrN6O2S
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