At 100 MHz each photon has energy equal to 6.62148x10^{26} joules.
One watt is equal to one joule per second, so 1000 watts is 1000 joules per second.
This equates to 1000/6.62148x10^{26}, or about 2x10^{24} photons per second.
As Davenn said, this number is so large that we don't even use it. One trillion is only 10^{12}, so there is literally 2 trillion trillion photons! (2 x 1 trillion x 1 trillion)
