In Chinese, 亿万 just means multiple 亿, not 万亿!
At old times, there was often saying 亿万 people. But China has never got population of 万亿, neither does the whole world. China's population peak in history was only a little more than 13 亿, and the whole world's population peak in history was only between 40 and 50 亿.
Does this make sense to you now?