A lot of sentiment here seems to be that Project Euler is more about math than programming. I feel like that depends on ones definition of the term programming. Computer science of course has nothing at all to do with computers as it only asks the question "What can be computed?" and Project Euler is very much in this spirit just as Knuths "The Art of Computer Programming" is. For example many of the problems require you to use specific algorithms to find an answer in polynomial time.

If you define programming as software engineering then of course Project Euler is mostly irrelevant. But computer science is math, not software engineering.