US President Donald Trump saw his rank slide 220 spots on the list to 544, with his wealth now estimated at US$3.5 billion, a decline of US$1 billion from previous year.
Goh Cheng Liang, who holds a 39 per cent stake in Japan's Nippon Paint holdings, remains Singapore's richest man with a net worth of US$6.5 billion and a ranking of 219 on the Forbes list.
Forbes' staff determined that 2017 was a "record year for the richest people on earth", concluding that the number of top earners rose from 1,810 in the world last year to 2,043 billionaires for 2017.
Facebook creator Mark Zuckerberg was number five and Oracle co-founder Larry Ellison was number seven.
The number of women on the list increased by 25 from 2016, with 2017 having the highest number of female billionaires ever at 227.
Trump hasn't released his tax returns, but during the election campaign he claimed to be worth in excess of $10 billion.
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There are no surprises at the top with Microsoft co-founder Bill Gates at number one for the fourth year in a row.
Forbes cites a weak real estate market in Manhattan for the President's drop.
"Although Donald Trump's name is plastered on buildings all around the world, his core assets are still located in a small part of New York City", Forbes associate editor Dan Alexander said about Trump's ranking the publication's famous annual listing.
Gayle Cook had previously made regular appearances on Forbes' lists until she transferred her wealth to her son. Last year, they estimated him to be worth upwards of $3.7 billion.
The country with most of the billionaires, a record 565 (28 percent), is the United States, followed by a fast-rising China (319).
Tech billionaire Bill Gates met with President Donald Trump to discuss progress in programs for global health and development as well as domestic education. Last year, he ranked No. 7.
Amazon founder Jeff Bezos ranks third on Forbes' richest billionaires list.