It was seen taking off from a US Air Force base, which is part of Air Mobility Command. A great deal of their operation is departing or returning troops from abroad, so it gets a lot of rare visits from oddball commercial aircraft.
This 747 had the short 3-window upper deck area, so it was a -100,-200 or SP, and it wasn't an SP. It was a "white tail", entirely white except for some numeric markings.
No USAF marking, that's not a surprise since the Air Force has six 747-100/200s: all accounted for by four NEACP planes (why would they come to an AMC base?) and two VIP transports (and they have a distinctive paint scheme, so, I wouldn't be asking).
It did not carry the distinctive markings of several Arab state head-of-state aircraft, the NASA paint scheme, nor the Las Vegas Sands Corp. scheme, nor Earnest Angley Ministries. It did not have any funny engines on it. Kalitta Air doesn't fly them anymore.
I have to assume none of the nine in Iranian service would be visiting a USAF/AMC base.
I'm sorry, I tried to get a photo, but could not safely stop. What could this airplane be?