Are Arabic numerals a language?

It was a quiet night and I spent all night studying. I got a question after reading Linguistic Knowledge. Are Arabic numerals a language? People around the world know the form of 1,2,3,4,5,6,7,8,9,and 0. However, there are no unitive titles. People around the world use their languages to pronounce and define Arabic numerals. I wonder why Arabic numerals can be understood by human being. On the contrary, why people cannot understand Roman numerals as well as Arabic numerals? Are Roman numerals old language? I will ask my professor tomorrow.