The sum of 20-year principal and interest = 400 * (1+5%) (20 *12) = 48,695,829.5 yuan.

If you invest every month, it will exceed 654.38+0 billion yuan.

I use an annual income of 5%, compound interest every month, which is more practical.

f=400*( 1+5%/ 12)*(( 1+5%/ 12)^(20* 12)- 1)/(5%/ 12)= 165,098.52

The above answers, I hope to help you.