This will depend on the type of sugar, but since glucose is the standard as far as sugars go, we'll use it. The chemical formula for glucose is C6H12O6, meaning it has six carbon atoms, twelve hydrogen atoms, and six oxygen atoms, for a total of 24 atoms. If you have 1000 glucose molecules in a crystal, you have a total of 24,000 atoms (24 X 1000).
One molecule of glucose sugar contains 6 carbon atom, 12 hydrogen atom, and 6 oxygen atom. So there are 24 atoms present in one molecule of glucose sugar.
So if there are 1000 molecules of glucose sugar present in a sugar crystal than there will be 6000 carbon atoms, 12000 hydrogen atoms, and 6000 oxygen atomswill be present making a total of 24000 atoms in 1000 molecules of sugar crystal.
Therefore, there will be 24000 atoms present in 1000 molecules of sugar crystal of glucose.