Bill Gates, with a Net Worth of around $75 billion, is officially the richest man in the world. However, some experts believe that Russian leader Vladimir Putin's fortune -- the extent of which has long been a closely-guarded secret -- more than doubles that of the Microsoft founder.

Fund manager says Putin could be worth nearly $200 billion

Political analyst Stanslav Belkovsky placed Putin's net worth in the neighborhood of $40 billion in 2007. But the latest estimate of the leader's wealth, according to former fund manager and author Bill Browder, is upwards of $200 billion -- unofficially making Putin the world's richest man.

But don't expect to see Vladimir Putin on the cover of Forbes magazine any time soon.

According to Forbes, the magazine's list of wealthiest people excludes world leaders, particularly "dictators who derive their fortunes entirely as a result of their position of power." Putin, however, did earn the top spot on the magazine's list of most powerful people in the world.

Vladimir's collection of toys

While the extent of Putin's fortune may be a secret, the Russian leader is fond of showing off his wealth. There's his $35 million yacht, the $1 billion palace on the Black Sea -- just one of 20 of the president's residences -- a personal collection of rare watches valued at half a million, and up to 58 private jets and helicopters.

A report from a political rival alleges that Putin's primary private jet is valued at $137 million and features a golden toilet which alone is worth $62,000.

Belkovsky's 2007 report on Putin's assets claims that the bulk of the leader's wealth is due to his 37 percent ownership in the oil company Surgutneftegaz. Putin also has significant holdings in the natural gas company Gazprom, and was rumored to have a stake in the commodities trader, Gunvor.

Gunvor, however, denies this claim.

According to Daily Mail, in April of 2015 Putin declared a 2014 income of just $119,000, listing two apartment buildings and a share of a parking garage as his most significant assets.