During his final Presidential Medal of Freedom ceremony as president, President Obama awarded 21 people the highest U.S. civilian honor on Tuesday.

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Among the recipients were Richard Garwin, a polymath physicist who earned a Ph.D. at age 21 and made pioneering contributions to U.S. defense and intelligence technologies; Bill and Melinda Gates; Frank Gehry, an architect who designed the Walt Disney Concert Hall in Los Angeles and the Dancing House in Prague; and Eduardo Padrón, the president of Miami Dade College.

Two recipients, Grace Hopper, "the first lady of software," and Elouise Cobell, an advocate for Native American women and communities, were honored posthumously.

Nearly a dozen celebrities recieved the honor, including Ellen DeGeneres, former NBA player Kareem Abdul-Jabbar, Tom Hanks, Robert Redford, Robert De Niro, Diana Ross and Bruce SpringsteenCicely Tyson, Vin Scully and Lorne Michaels, best known for creating and producing "Saturday Night Live," also received medals.

DeGeneres was became emotional as Obama fitted the medal around her neck.

"It's easy to forget now when we've come so far where now marriage is equal under the law just how much courage was required for Ellen to come out on the most public of stages almost 20 years ago," Obama said. "How important it was, not just to the LGBT community but for all of us to see somebody so full of kindness and light, somebody we liked so much, somebody who could be our neighbor or our colleague or our sister, challenge our own assumptions, remind us that we have more in common than we realize, push our country in the direction of justice."

Obama made the crowd laugh when he fitted Abdul-Jabbar with a medal, as the 6-foot-1 president is significantly shorter than the 7-foot-2 sports legend, and again when he reminded the audience that Air Jordans might never have existed because Jordan almost cut off his big toe with an axe at the age of 5.

"He's more than just an internet meme," Obama said. "There is a reason you call somebody the 'Michael Jordan of' -- the Michael Jordan of neurosurgery or the Michael Jordan of rabbis ... and they know what you're talking about. Because Michael Jordan is the Michael Jordan of greatness. He is the definition of somebody so good at what they do that everybody recognizes them."

Obama told the audience that to Americans Scully is "an old friend" and that he considered having Scully, a famed sportscaster, present the medals.

Speaking of Hanks, Obama joked that he "fell in love with Meg Ryan three times" and "made it seem natural to have a volleyball as your best friend."