Passage: On 10 January 2007, Queen Mary 2 started her first world cruise, circumnavigating the globe in 81 days. On 20 February, she met her fleet-mate, Queen Elizabeth 2, also on her 2007 world cruise, in Sydney harbour.  This is the first time two Cunard Queens had been together in Sydney since the original Queen Mary and Queen Elizabeth served as troop ships in 1941. Despite the early arrival time of 5:42 am, the Queen Mary 2's presence attracted so many viewers that the Sydney Harbour Bridge and Anzac Bridge were blocked. With 1,600 passengers leaving the ships in Sydney, Cunard estimated the stopovers injected more than $3 million into the local economy.On 10 January 2012, the ship embarked on a three-month world cruise from Southampton, travelling south and then east around Africa, a first ever circumnavigation of Australia, to Japan, then back to Southampton along the south coastline of Eurasia and through the Suez Canal.

Question: How many days long was the cruise?
81