What is 20000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000called?

The number you've written is called "two hundred quindecillion" in the short scale system, which is commonly used in the United States and modern English-speaking countries. In scientific notation, it can be expressed as (2 \times 10^{82}). In the long scale system, which is used in some European countries, it would be referred to differently, but the short scale is more widely recognized today.