Mannitol is isomeric with sorbitol, differing only in the stereochemistry at carbon atom 2.
Molecular formula: C6H14O6
Molecular weight: 182.17
Mannitol has water solubility of about 0.2 g per mL.
See my essay "Polyols--Digestive Issues" for a discussion of the potential gastrointestinal effects of polyol consumption.