15,320,506 is fifteen million, three hundred and twenty thousand, five hundred and six
15,921,737 is fifteen million, nine hundred and twenty-one thousand, seven hundred and thirty-seven.
5284000 or 5,284,000
Two trillion three hundred ninety-nine billion nine hundred fifteen million. Or, 2,399,915,000.
Nine billion, five hundred fifteen million, two hundred one thousand, one hundred ten.
One and fifteen hundredths of a billion or, more usefully, one billion one hundred and fifty million.