Unfortunately you can trademark just a work or a number.
The number 3 is trademarked by nascar
26.2 and 13.1 by sports apparel companies
And the word Apple by, well, Apple
Those are just a few example.
Hang on, this is a little misleading. The number '3' is trademarked by NASCAR
as it pertains to stock car racing. It may even be specific to the stylization of it. If you want to slap the number '3' on a bottle of IPA, there's nothing they can do to stop you.
Likewise, if you want to start a brewery called "Apple Brewing," that's perfectly fine. You can start the "Apple T-shirt Company," "Apple Airlines," or "Apple Snowshoes." You just can't start a music company, computer company, phone company, tablet company... anything that overlaps with their current business lines.
Apple actually got into trouble over this with a British music label that owned the rights to the Beatles' library (they're named "Apple Music" or "Apple Records" or something). When Apple first started up a long time ago, the record label sued them. They eventually settled, but Apple agreed to stick to computers, and not venture into the music industry.
Well fast-forward to the invention of the iPod and the advent of iTunes, and the British company got a little p*ssed (and rightfully so). They eventually settled again, with Apple writing a huge (undisclosed) cheque. That's why it took so long for the Beatles' music to be available on iTunes, and why they made such a big deal about it when it finally did.