You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2S,4S,5R,6R)-5-acetamido-2-[(2S,3R,4S,5S,6R)-2-[(2R,3S,4R,5R,6R)-4,5-dihydroxy-6-[(E,2S,3R)-3-hydroxy-2-(icosanoylamino)octadec-4-enoxy]-2-(hydroxymethyl)oxan-3-yl]oxy-3,5-dihydroxy-6-(hydroxymethyl)oxan-4-yl]oxy-4-hydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]oxane-2-carboxylic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C61H112N2O21
assistant