A seven letter word with a thousand letters in it would be: a mailbox.
Mailbox
mailbox
seven hundred and eighty
Seven hundred and forty-nine.
mailbox
mailbox
Seven hundred and forty-nine.
Fifty-six thousand, two hundred thirty-seven hundred-thousandths.
one billion, four hundred and twenty seven million
With letters it's written eighteen billion seven hundred million.
Five million, seven hundred and seventy-three thousand, nine hundred and sixty-three.
Seven million eight hundred and eighty five thousand six hundred and nine point three seven
Fifty-eight thousand, seven hundred and fifty-two dollars
700 = seven hundred