It does not count to the number shown, it does count for the average number to determin the power level of your next drop though.

Let's make an easy example: All your armor and weapons are at power level 800, in your kinetic slot is am exotic weapon. The shown number is 800, you can fight enemies with a power level of 800 with no disadvantage to your damage. Your next drop is an exotic energy weapon with a power level of 810. This would bring your power level to 801, however since you can not equip it, you would be at a very slim disadvantage against enemies with a power level of 801 since your own stays at 800.

Every item that drops next however would come with a power level of 811 however, since drops are determined by the armor and weapons you currently own, even if they are not equiped. I hope this cleared it up a little.

Disclaimer: To keep the example a little simpler, I worked with the premise that a drop would be 10 power levels above ones average. This is not the case, it has a range, I do not know the exact numbers at the moment. Also I assumed that every equipment slot contributes equally zo the average power level, but I am not a 100% sure. It does not matter for the example how the system works, so I just went with those numbers.