You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 4-[4-(5-chloroimidazo[1,2-a]pyridin-6-yl)phenoxy]-N-ethoxypiperidine-1-carboxamide by IUPAC nomenclature, provide its molecular formula.
user
C21H23ClN4O3
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