The specs are: 64-bit required. 32-bit is finally dying, I would expect to see more and more games that won't run on 32-bit.
32-bit restricts you to slightly less than 4GB of total addressable memory. That includes system RAM, graphics card memory, and a few other bits and bobs added together. My modest graphics card has 3GB of RAM... use all of that and there's not much left for anything else