DCLXI

DCLXI is the Roman numeral for the number 661. In Roman numerals, the letters D, C, L, X, and I represent 500, 100, 50, 10, and 1 respectively, and they are combined to form 661 (500 + 100 + 50 + 10 + 1).

As a calendar designation, DCLXI denotes the year 661 in the Anno Domini or Common Era system, or 661 BCE in the Before Common Era system, depending on the chronology being used. In widely cited historical contexts, the year 661 CE is notable for events surrounding the early Islamic caliphates, including the assassination of Ali ibn Abi Talib and the rise of Mu'awiya I, who established the Umayyad Caliphate with its capital at Damascus. The Byzantine Empire was ruled by Constans II during this period (r. 641–668). These events reflect a broader pattern of political realignments and conflicts in the 7th century.

In modern usage, DCLXI can appear in scholarly texts, inscriptions, or cataloging systems as a numeric marker. It may be encountered on historical coins, stone inscriptions, or editioned works that employ Roman numerals for sequencing or dating.

See also: Roman numerals; list of Roman numerals.