No.
3000 + 200 + 20 + 3
I write 620 billion as 620 billion.
Sixteen point two billion is how I would write it.
You write 3.56 billion as 3,560,000,000.
11, for one.
You can write 40.3 billion as 40,300,000,000.
You can write out 1.8 billion as "1,800,000,000" or "one billion eight hundred million."
Since you asked how I would write the number, the answer is 1031.
1,000 billion billion is: 1,000,000,000,000,000,000,000
35.9204067 billion
Approximately 3223