21
Houston Astros: 8 players don No. 21 on Roberto Clemente Day
Retire No. 21 for Roberto Clemente - Our Esquina
Uniform number (Major League Baseball) - Wikipedia
Report: Puerto Rican MLB Players Allowed to Wear No. 21 on Roberto Clemente Day, News, Scores, Highlights, Stats, and Rumors
All of MLB's Puerto Rican players can wear No. 21 on Roberto Clemente Day
Puerto Rican players pushing for MLB to retire Clemente's number
Rangers, MLB honor late Hall of Famer Roberto Clemente with uniform patch, jersey numbers
Ríos, Hernández to wear uniform No. 21 on Roberto Clemente Day, by Rowan Kavner
Pirates will honor Roberto Clemente by wearing his No. 21 on their jerseys - ESPN