With 33,510,157 followers for @BarackObama as of July 1, the president is the fourth most followed person in the world, just behind Lady Gaga, the report said. Pope Francis is in second place among world leaders and heads of state with 7,200,332 followers for nine @Pontifex accounts.
The report, "Twiplomacy," was prepared by Burson-Marstellar, an international consulting firm with its headquarters in New York.
The study found 77 percent of the 193 countries that belong to the United Nations are on Twitter.
While Obama -- or his staff -- put out a lot of tweets to a lot of people, the president has established mutual Twitter relationships with only four other leaders. About one-quarter of world leaders follow him unilaterally.
Swedish Foreign Minister Carl Bildt has 44 mutual relationships with other secretaries of state for @CarlBildt. Ugandan Prime Minister Amama Mbabazi puts out few tweets with 96 of those he sends on @AmamaMbabazi being responses to other tweets.