You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 6-(cyclopropylmethyl)-10-(1H-indole-6-carbonyl)-2-oxa-6,10-diazaspiro[4.6]undecan-7-one by IUPAC nomenclature, provide its molecular formula.
user
C21H25N3O3
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