More than 1.5 billion Formula One fans tuned in to watch the titanic title battle between seven-time world champion Lewis Hamilton and Red Bull rival Max Verstappen unfold over the course of the 2021 season, according to viewership and attendance numbers released by the sport on Thursday.

Cumulative TV audience for the 22-race season reached 1.55 billion, up four percent over 2020.

Unsurprisingly, the controversial season-ending Abu Dhabi Grand Prix, with Verstappen and Hamilton level on points going into the final race, drew the highest viewership of the season with 108.7 million viewers tuning in, 29% higher than the viewership recorded by the Yas Marina finale in 2020.

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Verstappen won the drivers' title after an altered safety car restart procedure allowed him to pass race-leader Hamilton on the final lap seven corners from the finish.

Mercedes clinched an unprecedented eighth straight constructors' title.

“The 2021 season was something very special," said Formula One chief executive Stefano Domenicali in a statement.

"We had a championship battle that went to the last race with huge excitement throughout the whole championship."

With Verstappen fighting for his first title, the Netherlands registered the highest growth in cumulative viewership at 81% over 2020.

The United States, where the sport has seen its popularity surge thanks in large part to Netflix show 'Drive to Survive' and which is set to host two races in 2022, also saw strong growth, with viewership going up 58% year-over-year.

The sport saw 2.69 million spectators attend races at the track, after COVID-19 imposed restrictions in 2020.

The US Grand Prix in Austin, Texas was the best-attended race of the season with 400,000 fans turning up over the weekend followed by the Mexican Grand Prix (371,000 fans) and Hamilton's home British Grand Prix at Silverstone (356,000 fans).

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Half of the season's 22 races saw crowds of over 100,000 including the rain hit Belgian Grand Prix (213,000) which was called after a minimum number of laps behind the safety car.

Verstappen's home Dutch Grand Prix at Zandvoort, which returned to the calendar after a 35-year absence, saw 195,000 of his orange-clad fans packing the grandstands.

Overall attendances were lower than the pre-COVID 4.16 million but the sport expects spectator numbers to bounce back once the pandemic subsides.

On the digital front, F1's followers grew 40% to 49.1 million, making it the year's fastest-growing major sport in terms of follower growth.

F1 is set for a record 23-race season this year starting with the Bahrain Grand Prix on March 20.