The " XXI " in capitals mean 21 in Roman numerals, but I don't think the lower-case letters " xxi " here also refer to 21. It seems that the sentence is well understood if the "xxi" is removed.
0 I was taught XXI or 21c. for twenty first century. The most important part being that the reader understands the writers intention.
Nowadays, we often see the word impact being used as a verb. It has been a verb since the 17th century. 1601 P. Holland tr. Pliny History of the World II. xx. xxi. 73 The seed of this hearbe remooveth the tough humours bedded in the stomacke, how hard impacted soever they be. 1677 T. Gale Court of Gentiles: Pt. IV iv. Proem 4 Ideas or notions impacted on the mind. Should the verb "impact" be ...
False Philol. 60 To obtain an agential substantive complementing the verb photograph. 2003 L. K. Graham in J. N. Poling & C. C. Neuger Men's Work in Preventing Violence against Women v. xxi. 368 Until she sought help..Anna was a rather helpless receptor..of her husband's agential power used violently to subordinate and control her.
Oil and natural gas producer Energy XXI will become a bigger player in the shallow waters of the Gulf of Mexico under a deal to buy certain offshore assets from Mit Energy Upstream, a unit of Japan's ...