The Roman number DXXVI corresponds to the arabic number 526.
There is no common alternative notation for this number.
You are looking for acronyms beginning with DX? Here is our list with acronyms starting with DX.
Interesting Fact: From the 14th century on, Roman numerals began to be replaced by Arabic numerals; however, this process was gradual, and the use of Roman numerals persists in some applications to this day.