[oblio]

> XXIer century

Sorry, but it's a bit funny. Based on the name I assume you're French (speaking, at least)?

That "XXIer" contraption is really funny to me, I speak a bit of French. In English it's twenty first so XXI or XXIst, in French as far I know it's vingt et unième, so XXI or XXIème.

Is "XXIer" from another French dialect or another language entirely?

[femtozer]

As a french person, it looks weird to me. I would only use it for the very first century: Ier siècle.

[fmajid]

Probably German (Zwanzig Erster)

[oblio]

See, that's the problem with (my) assumptions :-D