You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(1E)-1-[[2-(3,4-dimethylphenyl)-5-methyl-3-oxo-1H-pyrazol-4-yl]methylidene]-3-(4-methylphenyl)urea The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H22N4O2
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