Last month, LaDainian Tomlinson signed a one-day contract to retire as a San Diego Charger. A few days later, Roger Clemens was acquitted on all accounts of obstruction and lying to Congress about the use of performance-enhancing drugs. Meanwhile, the New Jersey State Senate will vote Thursday on a resolution aiming to request that Major League Baseball retire the No. 21 in honor of Roberto Clemente, as they did in 1997 with Jackie Robinson's No. 42.

Besides the involvement of superstar athletes, these stories seem to have little in common -- but by simply scanning the back of their jerseys, you'll find that they all wore the No. 21. And they're not the only sports legends to sport the number:

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