That is what Mahtook's late father -- also called Mikie -- wore as a football player at LSU. It is the number the son puts on his cleats and carries in his heart as he carves out his athletic identity while remembering his legacy.
"I know every day my father is with me," said Mahtook, who is No. 95 on MLB.com's list of the Top 100 Prospects. "Every day I try to honor him."
Mahtook does that by being just as gung-ho in baseball as his father was as a Southeastern Conference linebacker for the Tigers.
The speedy right-handed hitter passed on an opportunity to play college football himself so that he could give baseball his full-time attention. But the football mentality that is part of his heritage never left him.
"That's the only way I know," said the native of Lafayette, La. "I play as hard as I can and have as much fun as I can. I'm intense."
Mahtook was just four years old when his father collapsed and died of an enlarged heart at age 32, so most of what he knows about his father comes from stories passed down by his uncle Robbie, who also played football for LSU, and others.
There was little doubt that Mahtook, an All-State football and baseball player, would follow in his father's footsteps and head to LSU, and he quickly established his own identity once there.
Mahtook helped the Tigers win the College World Series as a freshman and left LSU after three seasons with a .344 career average. As a junior, he led the SEC by hitting .383 and stealing 29 bases.
Mahtook, 22, waited until the signing deadline last August before agreeing to a bonus deal worth $1.15 million with the Rays and didn't see any Minor League action last season. But he hit .338 for the Surprise Saguaros in the Arizona Fall League, convincing Tampa Bay that he was ready to be pushed up the Minor League ladder.
After getting five hits in his first three games in the Class A Advanced Florida State League, Mahtook experienced a bit of a reality check. But he was 11-for-33 in the last nine games of April to get his average up to .284.
He had nearly as many walks (eight) as strikeouts (13) while posting a .354 on-base percentage, and he had 10 RBIs in April. On the negative side, though, he managed just three extra-base hits for the month and was caught on three of his seven steal attempts.
"This is a tough league," Mahtook said. "There are a lot of good pitchers and a lot of good players."
Public address announcers around the Florida State League have not always gotten Mahtook's name right, a problem he's always had to live with. For the record, it is pronounced Mike-eee MAH-took.
"It's constantly wrong," Mahtook said. "I get Mickey May-took or sometimes Mah-hook, whatever. I don't think it should be that hard."
And it is important to Mahtook to have the name right. After all, it was his father's. Once they were Big Mikie and Little Mikie. Now the son carries his late father's uniform number with him on his cleats every time he takes the field as a constant connection.
"I feel like whenever I need him, he's there for me," the Rays prospect said.
One-two punch: Lakeland teammates Avisail Garcia and Nick Castellanos had the top two batting averages and slugging marks in the Florida State League for April. Garcia, an outfielder, batted .400 and slugged .565, while third baseman Castellanos was just behind at .398 and .545. Castellanos is ranked as the Tigers' No. 2 prospect, while Garcia is No. 8.
Colvin rewarded: Clearwater right-hander Brody Colvin, the Phillies' No. 3 prospect, got his first victory after two losses, allowing one run over six innings Monday against Brevard County. He walked five but struck out seven. Colvin gave up just two hits over six scoreless innings in a no-decision two starts earlier.
Bombs away: St. Lucie outfielder Cory Vaughn, the Mets' No. 15 prospect and the son of former Major League slugger Greg Vaughn, homered in three straight games to move into a tie with Daytona's Greg Rohan for the league lead with five. Rohan had a monster April, finishing with 28 RBIs in 24 games.
Up and down: Jupiter left-hander Chad James, who lost his first 13 decisions a year ago, won his third start this season. But the Marlins' No. 4 prospect finished April with a 6.03 ERA to go with a 1-1 record in four starts. The first-round pick in the 2009 Draft bounced back last season to win five of his last seven decisions and finish 5-15 with the Hammerheads.