DCLXIV is a Roman numeral that represents the number 664. Roman numerals are a numeral system originating from ancient Rome, using combinations of letters from the Latin alphabet. In this case, "D" stands for 500, "C" for 100, "L" for 50, "X" for 10, and "IV" for 4. When added together, these values total 664. Roman numerals are often used today in various contexts, such as in the naming of monarchs and popes, or to denote the year of publication in books and movies. Understanding Roman numerals can enhance one's appreciation of history and culture, particularly in relation to ancient Rome and historical texts.