The number 21 in baseball is famously associated with Roberto Clemente, a legendary Hall of Famer who wore the number for most of his Major League Baseball career with the Pittsburgh Pirates. Clemente was not only an exceptional player, known for his hitting and fielding, but also a humanitarian who passed away tragically in a plane crash while delivering aid to earthquake victims in Nicaragua. His number 21 has been widely honored and worn by other players in recognition of his legacy. Roberto Clemente initially wore number 13 during his debut but soon switched to number 21, which he wore for the remainder of his career. MLB honors his legacy every year, especially on Roberto Clemente Day (September 15). On this day, many players wear the number 21 or patches with the number to commemorate his contributions to the sport and society. Additionally, all MLB players, coaches, and personnel wear a No. 21 patch to honor him, and Puerto Rican players or Clemente Award nominees can also wear the number on their jerseys.

So, in contemporary baseball, the number 21 can refer to Roberto Clemente’s enduring legacy, and players may wear it especially around Clemente Day as a tribute.