A US Billion has 9 digits following the leading number(s):
202,700,000,000
The European system uses a different billion than the US (although many countries have adopted the US Billion -- as it works better with currencies). That variation is a million million (12 digits following the leading number(s)):
202,700,000,000,000
cetre number 2027 seat number A192526
Since you asked how I would write the number, the answer is 1031.
19.35 billion = 19,350,000,000
As a number: 7,125,000,000 = 7.125 billion
As a number it is 12,800,000,000 = 12.8 billion
As a number it is: 6,080,000,000 = 6.08 billion
As a number it is: 24,600,000,000 = 24.6 billion
As a number it is: 529,600,000,000 = 529.6 billion
As a number it is: 1,800,000,000 = 1.8 billion
As number it is: 1,500,000,000
80 billion = 80,000,000,000
As a number it is: 1,000,000,000 = 1 billion