President Barack Obama

President Barack Obama's surprise announcement of Osama bin Laden's death Sunday night drew 56.5 million viewers, Nielsen reported. It's the biggest TV audience the president has attracted since taking office.

U.S. military operation kills 9/11 mastermind Osama bin Laden, President Obama announces

Viewership surpassed Obama's first address to Congress in February 2009, when some 52.4 million tuned in. His nine-minute speech at 11:35 p.m. EDT Sunday was carried live by nine networks.

Osama bin Laden's death sets record on Twitter

Interest in Obama's speech grew as it was fueled by social media, and speculation started to focus on bin Laden's demise. About 35 minutes before the president spoke, there were 5,106 tweets per second. Anticipation was further stoked when the broadcast networks broke into regularly scheduled programming by 10:45 EDT Sunday night.

Ratings: Bin Laden coverage skews figures

By comparison, Obama's first State of the Union address pulled in 48 million viewers and 42.8 million this year. American Idol grabs up to 25 million viewers, and last week's royal wedding averaged nearly 23 million in the U.S. Obama's March address about U.S. military action in Libya had 25.6 million viewers, according to Nielsen.