You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[(2S)-1-(ethylamino)-1-oxopropan-2-yl] (3R)-1-oxo-3-phenyl-3,4-dihydroisochromene-6-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H21NO5
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