Facebook IPO makes Mark Zuckerberg 29th-richest person on Earth

$19.1 billion dollars. That's how much Mark Zuckerberg is worth after Facebook Inc. sold 421.2 million shares valued for $38 each on Thursday.

Not bad for a guy who just celebrated his 28th birthday Monday.

Zuckerberg, who first showed up on Forbes' billionaires list in 2008 with an estimated net worth of $1.5 billion, is now richer than Google co-founders Sergey Brin and Larry Page, Bloomberg reports.

Facebook: Road to IPO

However, he's not quite as wealthy as Microsoft founder Bill Gates, who is worth $60.4 billion, or Oracle's Larry Ellison, who is worth $34.2 billion, according to Bloomberg's Billionaires Index. For that matter, Zuckerberg is also worth less than Michael Bloomberg himself, who Forbes estimates is worth $22 billion.

Of course, Zuckerberg isn't the only person seeing a huge windfall from Facebook's $104.2-billion valuation. As Bloomberg reports:

Dustin Moskovitz, 27, who roomed with Zuckerberg at Harvard and was the company's first chief technology officer, is now worth $5.1 billion.

Eduardo Saverin, 30, who has created headlines this week when it was revealed that he renounced his U.S. citizenship, is now worth an estimated $2.7 billion.

Christopher Hughes, 28, who recently bought theWashington, D.C.-based magazine the New Republic, may now be worth $836 million.

And Facebook's Chief Operating Officer Sheryl Sandberg, 42, who owns 27 million shares -- including 25 million in restricted stock units -- is now a billionaire.