Philadelphia 76ers obtain 7-foot-2-inch Dikembe Mutombo, last great center still standing in Eastern Conference, in six-player deal with Atlanta Hawks that will involve Theo Ratliff and Toni Kukoc going to Atlanta; Allen Iverson, Mutombo's new teammate, lauds move as one that will help 76ers win championship; Dikembe Mutombo looked as if he'd been playing with the Philadelphia 76ers for years instead of hours. Mutombo had 17 points, 13 rebounds and five blocked shots in his debut with the visiting 76ers, who beat the Detroit Pistons 99-78 Friday night. "He changed the whole game with his defense and rebounding," said Philadelphia's Allen Iverson, who had 43 points and 10 rebounds. Mutombo was traded with Roshown McLeod from Atlanta to Philadelphia on Thursday for Theo Ratliff, Nazr Mohammed and Pepe Sanchez and Toni Kukoc in the biggest deal of the season. After the game, Mutombo looked relieved to be sitting down with ice packs surrounding both knees. He flew from Atlanta to Philadelphia late Thursday night, had a physical at 7 a.m., then arrived in Detroit at about 5 p.m. Friday. "I need some sleep," Mutombo said. "But really, I'm so excited to be with this group. They're all about winning and we have a great coach." Sixers coach Larry Brown was glad that Mutombo provided a lot of the same things as Ratliff. "He rebounded and defended like he has his whole career," Brown said. "I thought he was terrific. . . . I think it's pretty remarkable what he was able to do under those circumstances." Philadelphia (42-14) has won six straight games. Denver Nuggets