Rich and generous

Microsoft co-founder Bill Gates held on to second place, growing his wealth to $56 billion from $53 billion last year, and investor Warren Buffett again came in third with $50 billion, up from $47 billion.

Buffett's Berkshire Hathaway Inc has fared better than Gates' Microsoft. Microsoft shares now trade about where they were a decade ago, while Berkshire shares have roughly doubled. Slim's major companies, which include Mexico's former state telecoms monopoly Telmex, have also seen stock price gains.

Forbes said that Gates would have still been the richest man in the world if he had not so far given $28 billion of his wealth to his foundation. He was only knocked off the top spot on the list twice between 1995 and 2010.

The wealth of the world's billionaires jumped 25 percent to $4.5 trillion and their average net worth rose to $3.7 billion from $3.5 billion. There were 47 people who dropped off the list, 42 who returned and 10 people who died. The number of women grew to 102 from 89 last year.

While positions have shifted, the top 20 was largely unchanged. New this year were Russian steel baron Vladimir Lisin, U.S. casino magnate Sheldon Adelson and manufacturing and energy billionaire brothers David and Charles Koch.

Adelson -- whose Las Vegas Sands Corp came close to defaulting on its debt last year -- posted the biggest increase in wealth behind Slim. His fortune grew to $23.3 billion from $14 billion, and he soared to No. 16 from No. 73 last year.

The Asia-Pacific's growth in wealth has also fueled a luxury goods demand, helping grow the fortune of Europe's richest man, LVMH Chief Executive Bernard Arnault, to $41 billion from $27.5 billion. He rose to No. 4 from No. 7.

"The global economy is recovering, but it is not all spread across the board," said Forbes. "Yes, there are increases (the number of billionaires) in Europe, but primarily it is Russia. The United States barely registered an increase."

"In terms of wealth, the dog that isn't barking is Japan," said Forbes, referencing a Sherlock Holmes novel. "(It has) a fairly small number of billionaires compared to the size of the economy."

The number of U.S. billionaires rose to 413 from 403, including three new Facebook billionaires -- Sean Parker, Eduardo Saverin and Dustin Moskovitz -- who join founder Mark Zuckerberg and Facebook investor Peter Thiel.

Moskovitz is also the youngest billionaire in the world at 26 and with a fortune of $2.7 billion, while the honor of being the oldest goes to Swiss tech billionaire Walter Haefner, who is 100 and worth $4 billion.

Canadian David Thomson, who owns Thomson Reuters, widened his lead over his financial news and data rival, New York City Mayor and Bloomberg owner Michael Bloomberg. Thomson rose three spots to No. 17 with $23 billion, while Bloomberg fell seven spots to No. 30 with a fortune of $18.1 billion.

Forbes ranked the billionaires' fortunes at the close of global stock markets on February 14, 2011. The full Forbes ranking of the world's billionaires can be seen at www.forbes.com/billionaires