(Reuters) - The Republican presidential candidates' prime-time debate on CNN attracted an average of 22.9 million viewers, the network said on Thursday, making it the highest-rated program in the channel's 35-year history.
The figures, based on Nielsen data, fell shy of the 24 million who tuned in last month when Republican candidates took part in a debate on Fox News Channel, the biggest audience for a non-sports telecast in cable TV history.
CNN's debate lasted three hours, one hour longer than the one on Fox News. The ratings for the CNN telecast covered the period from 8:15 p.m. to 11:15 p.m. ET, the network said.
Billionaire Donald Trump's blunt speaking style has boosted interest in the contest to pick a Republican presidential nominee for the November 2016 election. He shared the debate stage with 10 other candidates. Four other Republicans, who rank lower in opinion polls, took part in an earlier debate.
CNN charged up to $200,000 for a 30-second commercial during the three-hour event, according to people familiar with the matter.
Before the debate, Trump called on CNN to donate $10 million of advertising revenue from the debate to charity.
On Thursday, he made a simpler request: "Just announced that in the history of @CNN, last night’s debate was its highest rated ever. Will they send me flowers & a thank you note?" he wrote on Twitter.
Audiences for cable TV programs traditionally rank below the most-watched events on broadcast television. The Super Bowl U.S. football championship in January attracted 114 million viewers, while February's Academy Awards pulled in 37.3 million.
The debate also was streamed live on CNN's website for anyone to watch, even without a cable subscription. Viewership on the website and mobile apps peaked around 9:45 p.m. ET with 921,000 simultaneous streams, CNN said, a far higher Internet audience than previous primary debates.
By comparison, this year's Super Bowl peaked at 1.3 million viewers, CNN said.
CNN was founded in 1980.
Fox News Channel is owned by 21st Century Fox.
Reporting by Lisa Richwine; Editing by Doina Chiacu, Mohammad Zargham, Andrew Hay and Jonathan Oatis