In what year was the number one single from Rihanna that was featured on Now That's What I Call Music! 38 released?
Now That's What I Call Music! 38 (U.S. series):  The album features six tracks that reached number one on the "Billboard" Hot 100: "Born This Way", "S&M", "Hold It Against Me", "Grenade", "E.T." and "Rolling in the Deep". S&amp;M (song):  The song was released on January 21, 2011, as the fourth single from the album.
January 21, 2011