You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (3S)-4-[[(2S)-1-[[(2S)-1,6-diamino-1-oxohexan-2-yl]amino]-3-hydroxy-1-oxopropan-2-yl]amino]-3-[[(2R)-2-[2-(hydroxyamino)-2-oxoethyl]-4-methylpentanoyl]amino]-4-oxobutanoic acid by IUPAC nomenclature, provide its molecular formula.
user
C21H38N6O9
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