I sympathize with your gut feeling that the result just somehow doesn't seem right. Perhaps you could measure the area of the base of a gallon milk jug in square feet, look up how many square feet are in an acre, multiply that by 600, and then determine how many milk jugs would "carpet" that 600 acres. That might let you estimate how high you would have to stack milk jugs to get 1.4 million of them in that area. If no mistakes were made in any of that calculation, always something to be watchful for, then hopefully you will end up with "we would need to stack them two or three high." That might give you the needed gut feeling.
Many, maybe even most, people's gut feelings are often in error, sometimes wildly in error. Brains from a million years ago were never really intended to deal with calculations involving a few dozen digits. It is amazing we can learn to do any of this.
These errors in estimation are common and not easy to recognize when dealing with large quantities or long periods of time, especially when dealing with compound interest and exponential growth.
There are some good books out there that can teach you to estimate these sorts of calculations in your head in a few seconds, you have to learn the methods and practice. I used to be able to do compound interest and mortgage amortization calculations in my head.
But when people's agendas get involved or their vague, unstated, even unrecognized, feelings about "how the world ought to be" that was mostly put in place by the time they were age five then the actual facts and real data often make no difference at all, none, zero, More and more I am tending to believe that for most people and most of the issues that people are fighting about, the numbers, the "facts", don't make any difference and the only reason people are looking for those is so they can claim support for their position and discredit their opponent's position. I'd guess more of the numbers and facts are just made up or taken out of context than any of us realize.
I'm sorry.
