For the Record:.
In part that would depend on the mode of transportation and the longitude and lattitudes used. If you are at the North or South Pole you can simply run around the Pole twice...
This is a good one and a very popular question. We don't know. Some cruisers spend over 10 years getting around the world, some quit after 2 months. On average a circumnavigation takes 3-4 years.
It takes 4 weeks to travel round the world and back non stop with a day to do thing eg. get off plane at 10am get to hotel at 1pm play and go on a adventure from 1pm-6pm get dinner At 6:30 and get on...