Euler endeed lived in the 18th century and Riemann in the 19th (and not as erroneously stated in the article the 17th and 18th). Hopefully the authors will spot your comment and correct the mistake.
This typo aside, the article is excellent and very accessible. So it is a bit puzzling to me why some readers got it wrong, missed the point that the partial sums of a diverging series do not have a limit (other than infinity in certain cases) and they even left comments trying to prove one thing or another about some finite value for this nonexistant limit. Interestingly, some readers also missed the point about the analytical extension of the zeta function and stil left comments trying to interpret -1/12 as if it were the limit of the partial sums of a series (rather than a value of the extended function). Perhaps attention to detail could have helped, like yours spotting the century count typo.