You won't believe who's the youngest Indian billionaire in Forbes rich list!

Forbes Billionaires' list 2018 is finally out with India adding 19 new billionaires in 2018, taking the tally to 121 among 2,208 billionaires worldwide. With this, India has become the third largest group of the ultra-rich after US and China. 39-year old Vijay Shekhar Sharma, founder, Paytm is the youngest Indian billionaire, while 92-year-old Samprada Singh, chairman emeritus of Alkem Laboratories, is the oldest, according to Forbes. Sharma, ranked 1,394th on the list with a fortune of $1.7 billion, is the only Indian billionaire in the under-40 league. 

Sharma founded fast-rising mobile wallet Paytm in 2011. He has also created Paytm Mall, an e-commerce business and Paytm Payments Bank. 

"One of the biggest beneficiaries of India's demonetisation, Paytm has notched up 250 million registered users and 7 million transactions daily. Sharma owns 16 per cent of Paytm, which is now valued at $9.4 billion," Forbes said. 

Of the 2,208 billionaires in Forbes' 2018 list of the world's richest, just 63 are under the age of 40 and more than half (34) are self-made entrepreneurs. 

In all, the 63 youngest billionaires in the world are worth a collective $265 billion, up from $208 billion last year. 

Meanwhile, 92-year-old Samprada Singh, who is the chairman emeritus of Alkem Laboratories, is the oldest Indian billionaire. He was ranked 1,867th on the list with a fortune of $1.2 billion. 

Also read: Mukesh Ambani with $40bn, richest among 121 billionaires in India: Forbes

Singh founded the pharma firm Alkem Laboratories 45 years ago. Singh worked in a chemist's store before venturing out on his own distributing pharmaceuticals. 

"Shares of the generics maker, known for its antibiotics Clavam and Taxim, have more than doubled since its November 2016 IPO. For the year ended March 2017, Alkem reported a 20 per cent rise in net earnings to $139 million on revenues of $913 million," Forbes said. 

Meanwhile, Mukesh Ambani, the energy and petrochemicals magnate, kept his standing as the richest Indian. He is richer by $16.9 billion in 2018 with assets of $40.1 billion. He moved up to the 19th global rank. In 2017, he ranked 33rd with $23.2 billion.

(With inputs from PTI)