And billionaires' favorite city is …

Jessica Morris, special to CNBC.com

London is the European city the world's billionaires like to call home, according to research published by Beauchamp Estates and Dataloft.

There are 67 billionaires living in the U.K. capital and the city tops the ranks for Western Europe ahead of Paris (25 billionaires) and Geneva (18 billionaires).

Residential properties are seen in a street in Mayfair, London, U.K.
Jason Alden | Bloomberg | Getty Images

The survey by Beauchamp Estates and Dataloft looks at ultra-prime property values, billionaire lifestyles and billionaire property assets across Western Europe.

London's wealthiest reside in the so-called 'platinum triangle' which comprise the upmarket districts of Mayfair, Knightsbridge and Belgravia. Leafy St John's Woods and Regent's Park are also favorites.

Billionaires typically pay around £21.7 million ($36.1 million) for a Mayfair mansion, while similar properties in St John's Wood and Regent's Park go for around £22.3 million.

They tend to own four homes worldwide and on average, this includes a £22.3 million mansion in London; a £18.6 million holiday home on the French Riviera and a £12.1 million Tuscany estate.

And when it comes to choosing a mansion, a billionaire is most likely to be swayed by a property's location, size, outside space, security and design.

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The average billionaire is worth a whopping £1.79 billion. They generally hold 42 percent of their wealth (£750 million) in private holdings; 35 percent (£626m) in publicly-held companies; 18 percent (£325 million)in cash; 3 percent (£50 million) in residential real estate and 2 percent (£35 million) in luxury assets such as yachts and private jet travel, according to the report.

The survey also found that there are over 2,170 billionaires globally with a combined net worth of £3.88 trillion. Of these, 60 percent are self-made.

Holiday …

The French Riviera is the favorite for billionaire beach-side mansions and has around 39 such homes. The social calendar of a typical billionaire also lends itself to the location as it is in close proximity of the Grand Prix and Cannes Film Festival.

A six- to seven-bedroom beach mansion on the French Riviera costs around £18.6 million.

Other popular sunny spots include Tel Aviv/Israel (39), Tuscany (14) and Greece and the Greek islands (9).

Billionaire mansions on the Greek islands typically cost about £4.15 million.