IMO, it’s going to be in the thousands to 10’s of thousands. Depending on what organizations you exclude and if you’re considering total assets vs net assets vs liquid assets etc.

There’s a surprising number of individual buildings worth 1+ billion each of which are going to be their own org. Add pensions, trusts, nuclear reactors, large dams, government organizations, etc.

Here’s 30 US charitable foundations over 1B which isn’t an exhaustive list. https://en.wikipedia.org/wiki/List_of_wealthiest_charitable_...