A well-known joke/theorem is that all natural numbers are interesting. The proof goes as follows: assume that there exists a non-empty set of uninteresting natural numbers. Then this set has a smallest element. But that makes it interesting, so we have a contradiction. Incidentally, this proof applies to the integers and, with a bit of a stretch, to the rationals. It definitely does not applies to the reals, though, no matter how hard you believe in the axiom of choice.1
I was wondering, though, what is the smallest uninteresting number. It must exist, because we fallible humans are undeterred by the mathematical impossibility and simply do not find most natural numbers interesting.
Luckily, there is a objective criterion to determine whether a natural number is interesting: is there a Wikipedia article written about it? I then went through the Wikipedia articles about numbers, and found the first gap at 198. But now since this number became interesting, surely we should write a Wikipedia article about it?
This gives rise to another paradox: if we do write a Wikipedia article about 198 it will cease to be interesting, and of course we should delete the Wikipedia article about it. But this will make it interesting again, and we should again write the article.
You can see this paradox playing out in the revision history of the Wikipedia page: the article is indeed being repeatedly created and deleted.