Dikembe Mutombo was at a loss for words.

The former center and soon to be Hall of Famer will have his No. 55 retired by the Hawks. The announcement was made by Hawks CEO Steve Koonin during a ceremony in Fulton County Tuesday declaring Sept. 1, 2015 as Dikembe Mutombo Day. The news came as a complete surprise to Mutombo.

Mutomobo’s No. 55 will be raised to the Philips Arena rafters on Nov. 24 during a nationally televised game against the Celtics.

“The most surprising, as you can see from the tears in my eyes, is the announcement that was made (that my jersey will be retired),” Mutombo said. “It’s the most shocking to me. … I didn’t know the Hawks were going to retire my jersey. I can’t believe it. It’s going to be a great day.”

Mutombo played from 1996-2001 as part of an 18-year NBA career. He will be inducted into the Naismith Memorial Basketball Hall of Fame next week.

“When you look at the history of the Hawks and you see a player who made such a positive contribution, who is going to be Hall of Famer and who resides in Atlanta, it was two simple (phone) calls,” Koonin said. “One to (general manager) Wes (Wilcox) and one to Bud (president of basketball operations/head coach Mike Budenholzer) saying what you think? They couldn’t have been more enthusiastic.”

Mutombo will have the fourth jersey number retired by the franchise joining No. 9 of Bob Pettit, No. 21 of Dominique Wilkins and No. 23 of Lou Hudson.

Mutombo was an eight-time All-Star and four-time Defensive Player of the Year during his NBA tenure. He is the league’s second leading shot blocker and is 19th in rebounds. He was a two-time winner of the J. Walter Kennedy Citizenship Award by the league for his many humanitarian efforts.

Mutombo’s on- and off-court accomplishments were the reason for the declaration of Dikembe Mutombo Day by Fulton County and the Hawks. Board of Commissioners Chairman John Eaves made the declaration. Mutombo immediately left the ceremony for a humanitarian trip to China.

“It’s a big honor,” Koonin said the number retirement. “We have not done it for a lot of players. You talk about somebody with a career with several chapters in it and each one is a positive.”