SEATTLE — Just as much as the smile and the backward hat, the sweet swings and the 630 home runs, the No. 24 became synonymous with Ken Griffey Jr. Griffey chose it after hitting 24 home runs one season between his high school and summer baseball teams, and he wore it throughout his 13 seasons with the Mariners. “Baseball is all about numbers. Some of the greatest players to play in sports wore 24. It wasn’t planned but it was definitely one of the things when I signed my first contract that was one of the things I asked for was to be able to wear 24,” Griffey said Friday. “It’s extremely important. If you look at my first apartment in Seattle, it was 1124. My house number was 24606. There is a lot of things that have to do with 24.” Griffey is back in Seattle this weekend to see that famous No. 24 retired by the Mariners. His number retirement comes less than two weeks after he became the first player to go into the Hall of Fame as a Mariner. His number will be the first retired by the Mariners, and it will be set aside throughout the organization, not just with the major league club. The whole team will wear No. 24 during batting practice Saturday, and then it will be shelved forever. Griffey sounded humbled by the honor when he spoke Friday, in part because his number will hang next to Jackie Robinson’s No. 42 — retired throughout baseball — as the only numbers honored at Safeco Field. “An organization has to feel that it’s worthy and I know there are certain criteria that have to be met to even be mentioned and for a team to do that is the ultimate sign of respect for what you did on the field. It’s overwhelming, humbling because of the guy, the number I’m going up next to, who basically sacrificed his life for guys to play and that’s Jackie Robinson,” Griffey said. “It’s a weird feeling because of what he’s done and to allow pretty much everyone to play this game. And I’m going to be right next to him, so I haven’t really had a total grasp on it.” Seattle is pulling out all the stops for Griffey’s final honor of the summer, including commemorative hats, bases and balls for the games. Saturday’s retirement program could run as long as an hour in front of what could be the largest crowd ever at Safeco Field.