I've tracked my calories in, calories out and weight for extended periods over the last four years. I've had weeks where my rides burned far more calories than one would expect and just the opposite, too. While your number seems pretty high, it's probably possible and in any case the specific numbers are going to be different for every individual. In particular, the rules of thumb grow more inaccurate the farther someone is from an idealized "normal". A 150 pound person is going to have different energy expenditures than someone who is 300 pounds all else being equal, for example.

If you are willing to take the 15 minutes a day that it takes to log your food intake, weight and activities, you can learn a lot about how your body and it can be really interesting. With an HRM and enough other information you can even tell when you're getting a cold even if the symptoms aren't obvious yet.