Mutombo, a 7-foot-2 center who played all five of his seasons with Denver and led the league in blocks the last three seasons, signed a five-year contract believed to be worth at least $50 million.
"It was time for me to move on with my life," Mutombo said.
The Hawks also traded swingman Stacey Augmon and forward Grant Long to the Detroit Pistons for two first-round and two second-round draft picks.
The Portland Trail Blazers sent Strickland, one of the league's top point guards, and forward Harvey Grant to the Washington Bullets for Rasheed Wallace and Mitchell Butler. The Bullets also signed free-agent forward Tracy Murray for an undisclosed sum.
One player to stay put was Houston center Hakeem Olajuwon, who signed a five-year, $55 million contract extension with the Rockets. Olajuwon, 33, had just finished the first year of a four-year contract that gave him the opportunity to become a free agent next year.
A three-time all-star, Mutombo finished third in the NBA in rebounding this year, averaging 11.8 per game. He has averaged 12.9 points, 12.3 rebounds and 3.8 blocks a game over his career.
After Monday's wheeling and dealing, the Hawks are left without an experienced small forward.
"We will be making more moves," Hawk President Stan Kasten said.
Long, a 6-9 forward, averaged 13.1 points and a career-high 9.6 rebounds last season. Augmon, a 6-8 swingman, averaged 12.7 points and 3.9 rebounds.
The Pistons also signed two of their own free agents: guard Michael Curry and center Don Reid.
Strickland, who averaged 18.7 points and 9.6 assists in 67 games, walked out for six games last season, saying he would no longer play for Coach P.J. Carlesimo. He returned, however, to help the Blazers reach the playoffs.
Also Monday, Brent Price, a free agent point guard who spent the last three seasons with the Bullets, signed a seven-year deal with the Houston Rockets.
Houston's KRIV-TV, citing unidentified sources, said the deal was worth $18.2 million
(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)
NBA Free Agent Market
SIGNED, SEALED, DELIVERED
Player: Chris Childs
Team: New Jersey
Comment: Signed with New York Knicks for 6 years, $24 million
Player: Dale Davis
Comment: Re-signed with Pacers 7 years, $42 million
Player: Allan Houston
Comment: Signed by New York Knicks for 7 years, $56 million
Player: Juwan Howard
Comment: Signed with Miami Heat for 7 years, $98 million
Player: Michael Jordan
Comment: Re-signed with Bulls for 1 year, $30 million
Player: Dikembe Mutombo
Comment: Signed by Atlanta Hawks for 7 years, $70 million
Player: Gary Payton
Comment: Re-signed with SuperSonics for 7 years, $85 million
ALL BUT WRAPPED UP
Player: Tim Hardaway
95-96 Team: Miami
Pos.: Point Guard
Comment: Expected to re-sign with Heat
Player: Reggie Miller
95-96 Team: Indiana
Comment: Expected to re-sign with Pacers
Player: Alonzo Mourning
95-96 Team: Miami
Comment: Agreed to terms with the Heat for 7 years, $105 million
Player: John Stockton
95-96 Team: Utah
Pos.: Point Guard
Comment: Expected to re-sign with Jazz
STILL ON THE RACK
Player Team Pos. Kenny Anderson Charlotte Guard Hersey Hawkins Seattle Guard Derek Harper New York Guard Dan Majerle Cleveland Guard Robert Pack Washington Guard Steve Smith Atlanta Guard Latrell Sprewell Golden State Guard P.J. Brown New Jersey Forward Mario Elie Houston Forward Chris Gatling Miami Forward Armon Gilliam New Jersey Forward Brian Grant Sacramento Forward Horace Grant Orlando Forward Dennis Rodman Chicago Forward Otis Thorpe Detroit Forward Elden Campbell Lakers Center Antonio Davis Indiana Center Jim McIlvane Washington Center Oliver Miller Toronto Center Shaqulle O'Neal Orlando Center Sam Perkins Seattle Center Brian Williams Clippers Center