That's around 300 PPI, which is way more than enough; most photographs don't consist of super-high-contrast aliased lines, and thus will typically look OK print

That's around 300 PPI, which is way more than enough; most photographs don't consist of super-high-contrast aliased lines, and thus will typically look OK printed at considerably less than 300PPI; depending on context you could go as low as 100-200PPI. 300DPI is a bare minimum more because then the printer dots are bare visible; and of course you need many printer dots per pixel to be able to create smooth-looking gradients. It doesn't say as much about pixels. Of course, if you're printing sub-8MP images on a full page, then you can count on all those pixels being important, so any pixel-level defects that are usually hidden by their tiny size will become visible (hot pixels, noise, that kind of thing)