11 October, 2019
The answer, sadly, is yes. The “26.2″ you see on cars (in magnet form here), which is the length in miles of a standard marathon, was trademarked in 2008. It’s registered as a “standard character mark,” meaning that you cannot print the number 26.2 in any form on athletic wear (including shoes) or car stickers/magnets without violating the trademark.
I could spend all day in the “numbers that are illegal to use” rabbit hole, so I’ll leave you with just one more: NASCAR has a registered trademark for the number 3.