How many cores do I have?

I have an HP ProLiant ML350p G8 5U Tower Server

My invoice says "1 x Intel Xeon E5-2620 2GHz"

Windows system says "Intel Xeon CPU E5-2620 0 @ 2.00GHz"

Can't seem to find specific info concerning number of cores.

And if this is a single core processor, can this processor be swapped out for a multicore processor?

Thanks