According to research firm Wealth-X, which releases an annual Billionaire Census, there are 2,473 billionaires in the world.

Some countries are populated with hundreds of them. Take the United States, which is home to 585 — that's just under 25 percent of the world's billionaires.

After all, "billionaires like to be in areas where other billionaires are likely to be located as well," Wealth-X tells CNBC.

Here are the 11 countries with the largest populations of billionaires — and the total wealth held by the billionaire residents — courtesy of Wealth-X.