Denzel Washington has a line in “American Gangster” that could definitely apply to the pic’s lavish Gotham preem: “I took care of Harlem and Harlem’s going to take care of me.”

Universal’s tentpole arrived in high style Friday at Harlem’s Apollo Theater followed by a high-energy after-party in a tent next door.

It isn’t often you get the combo of Washington, Russell Crowe, Ridley Scott and Brian Grazer under the same tent, as an above-average number of fans snapped photos.

Scott, who stepped in for original helmer Antoine Fuqua, said the pic’s late-1960s/early-’70s Harlem setting wasn’t as foreign to him as it mightseem. “I spent a year in New York during the mid-1960s on a traveling scholarship from the Royal College of Art,” Scott said. “I took photographs all over the city, from Coney Island to Harlem.”

Grazer said Scott was the key to salvaging the pic after a rare production shutdown that saw Fuqua ankle over creative differences and U on the hook for $30 million in star salaries and other costs. “The last 40 minutes of the film are just staggering, and they show how we all got lucky when Ridley came on board.”