The interview in which the couple made accusations of racism, neglect and feuding inside the royal family aired on CBS on Sunday and on Britain's ITV on Monday. It is still available on streaming platforms.
CBS, a unit of ViacomCBS Inc, said the audience was still growing and it would rebroadcast the interview in the US on Friday.
The US television audience accounted for 17.8 million of the total, making it the highest-rated entertainment special since the February 2020 Oscars ceremony, CBS said.
Reuters