Khawaja is the 81st man to 15 Test hundreds. Considering he was viewed as an unfulfilled talent for much of his career, he finds himself in very elite company.
For context, the other players with exactly 15:
Clyde Walcott
Everton Weekes
Jack Hobbs
Doug Walters
Rohan Kanhai
Saleem Malik
Ramnaresh Sarwan
Chris Gayle
Angelo Mathews
Alec Stewart