You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule propan-2-yl (2S)-4-[[(2S,4aR,6R,7R,7aS)-6-(7-aminoimidazo[4,5-b]pyridin-3-yl)-7-cyano-7-methyl-2-oxo-4,4a,6,7a-tetrahydrofuro[3,2-d][1,3,2]dioxaphosphinin-2-yl]oxy]-2-methylbutanoate .
user
C21H28N5O7P
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