Microsoft co-founder Paul Allen is the world's wealthiest bachelor with a net worth of $15.3 billion, according to Wealth-X, a firm that researches ultra-high net worth individuals.
Allen, who has never married, is founder of Vulcan Capital and owner of football team the Seattle Seahawks, and basketball team the Portland Trail Blazers.
The richest 10 single billionaires have an average age of 54.5. The youngest bachelor in the list is 31 years old: Scott Duncan, who is worth $5.3 billion and is son of the late energy mogul Dan Duncan.
Here is a list of the 10 richest bachelors in the world:
quicklist:1 title: Paul Allen, 60 media: 21094460 category: $15.3 billion text:
Allen lives on Seattle's Mercer Island, but he recently bought a $27 million, eight-bedroom mansion in the Silicon Valley town of Atherton, which has the most expensive zip code in the U.S., according to Forbes.
Other billionaire residents in the Atherton area include Google chairman Eric Schmidt, HP chief Meg Whitman and brokerage founder Charles Schwab.
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quicklist:2 title: Giorgio Armani, 79 media: 21094808 category: $10.9 billion text: Italian fashion designer Giorgio Armani, called "the fashion world's perennial bachelor" by Wealth-X, has a net worth of nearly $11 billion.
The designer, who not only has a high-fashion clothing line, but hotels and fragrances, turns 80 in April 2014 and is the oldest person on Wealth-X's list.
quicklist:3 title: Mikhail Prokhorov, 48 media: 21094703 category: $9.3 billion text: Mikhail Prokhorov, 48, is owner of NBA team the Brooklyn Nets. The Russian entrepreneur and politician is the 69th richest person on the planet, according to Forbes.
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quicklist:4 title: Xavier Niel, 46 media: 21094532 category: $8 billion text: Xavier Niel, 46, is touted as "France's Internet king" by Forbes. His company, Iliad, is the parent of Free, a telecom. Last year, Niel launched mobile broadband company Free Mobile. He is co-owner of the French newspaper Le Monde.
quicklist: title: David Geffen, 70 media: 21095011 category: $6.6 billion text: David Geffen, 70, is an American businessman who co-founded DreamWorks Animation SKG.
quicklist: title: Marcos Mera, 42 media: 21095839 category: $5.7 billion text: Marcos Mera, 42, inherited the wealth of his late mother, Rosalia Mera, when she died in August. She was the world's wealthiest self-made woman from co-founding Spanish clothing brand Zara. The family's holding company is Rosp Corunna Participaciones Empresariales. Marcos Mera's sister, Sandra Ortega Mera, inherited more than 90 percent of their mother's wealth and became Spain's richest woman.
quicklist: title: Scott Duncan, 53 media: 21095773 category: $5.3 billion text: Heir to Enterprise Products Partners' late founder Dan Duncan in Houston, Scott Duncan, 53, and his three sisters have benefited from the energy company's stock price rise.
quicklist: title: Andreas von Bechtolsheim, 58 media: 21095341 category: $4.4 billion text: Andreas "Andy" von Bechtolsheim, 58, co-founded Sun Microsystems. He is chairman of networking company Arista Networks. The German bachelor is worth an estimated $4.4 billion.
quicklist: title: Alejandro Santo Domingo Davila, 36 media: 21095439 category: $3.9 billion text: Alejandro Santo Domingo Davila, 36, a Harvard graduate who is the second-richest person from Colombia, inherited the wealth from his father, Julio Mario Santo Domingo Pumarejo, who died in 2011. The Santo Domingo Group has interests in a range of businesses including SABMiller.
quicklist: title: Charles Butt, 75 media: 21095236 category: $2.9 billion text: Charles Butt, 75, is chairman and CEO of H.E. Butt Grocery in Texas.