Multiply by Avogadros constant, I make that something in the region of 6.7x10 to the power of 24 molecules. Multiply by three for the number of atoms, about 2 x 10 to the 25.
6.6 times ten to the 9 people in the world... There are many, many, many more orders of magnitude more atoms in a glass of water than there are glasses. Unless every person owns, like, 10 to the power of 15 glasses.