19 more than a year ago - making them the third largest group of the ultra-rich after those from the United States and China, according to Forbes, the business magazine that produces an annual list.
Ambani was ranked 20th previous year. Bezos has a fortune worth $112 billion and is now the world's richest person.
The U.S. has more billionaires than any other country with 585 people, while greater China - mainland China, Hong Kong, Macau and Taiwan - has 476.
His net worth dropped from $5.6 billion last year to $5.4 billion this year.
Software company HCL's founder Shiv Nadar is the fourth richest Indian on the list with $14.6 billion and is ranked 98 globally.
The US president was placed as the 544th richest person on the magazine's list past year but has now dropped to 766th, with more than $400 million wiped off his wealth.
The steep rise in Amazon's shares have made him America's only centi-billionaire by amassing over $100 billion in wealth. Ma Huateng (also known as Pony Ma) is Asia's wealthiest person, ranked number 17 in the world, thanks in part to his firm Tencent's WeChat, a ubiquitous social-messaging app with almost 1 billion active users.
This marks a decrease from the 2017 list, when he was No. 544 on the list with a net worth of $3.5 billion.
Forbes adds while Trump's $3.1 billion fortune is "a far cry" from the $10 billion-plus he once claimed, it still makes him the richest president in US history. He owns Amazon, which he founded in a garage in Seattle in 1994. Berkshire Hathaway founder Warren Buffet ($84 billion) and French business tycoon Bernard Arnault, and his family ($72 billion), rounded out the top five.
"The last time Trump's net worth was this low on the global billionaires' list was in 2012, when we put his net worth at $2.9 billion", Alexander said.