A record number of viewers are expected to watch the X Factor final results show on ITV Sunday night, generating an estimated £20-25m in ad revenue for the embattled broadcaster.The price for prime-time slots during the final has hit £250,000, or over £8,000 per second and because the final has been split over two days, analysts predict it could generate record revenues for a single TV show.ITV was allowed to show up to twenty-four 30-second adverts an hour during both the two-hour final performance show and the two-hour results show. The minimum price of the slots was £200,000, some 50% higher than normal prime-time rates.Advertisers on last night's show included Waitrose, BT, Apple and Nintendo, while Christian Dior and Electronic Arts are said to have picked up slots for the Sunday show.More than 18m viewers are reported to have watched the final, with viewing figures set to top 20m for the results show. The X Factor is expected to help to boost ITV's December advertising sales by 10% over last year.