There are more than 2,208 billionaires on the planet, as listed by Forbes. Because becoming rich takes time, the average age of those billionaires is 66 years old. But some of the youngest billionaires are in their early to mid-20s. Some of these billionaires worked tirelessly to make their riches, but not everyone had to work hard to get to the top. For some, bank accounts, company shares, and businesses were already waiting for them when they were born. The 63 youngest billionaires are worth $265 billion collectively, according to Forbes, and $61 billion of that is Mark Zuckerberg’s massive share. Here are the 20 youngest billionaires in the world, all of whom are under 40.

Editor's Note: This was first published on July 23, 2016.