provide calculation

What will be the population of the United States if its current population of 320 million (as of this writing) grows at a compound rate of 6.1% annually for 20 years? Round answer to nearest whole person-fractional people wouldn't be good (sounds like splinching - ). So-for this question, no decimal point, no zero's after, just whole numbers! Example: 123,456,789.53 people would be written as 123456790