"This is really Michelle fever in China," he said.
The embassy did not return a request for more information on how they tallied the number. It's unclear whether the number came from page views on the embassy's Web site or other sources, and whether the visitors to those pages were from China or other countries. China has a population of 1.35 billion.
Cheng said Obama and her family -- her mother, Marian Robinson, and daughters, Malia and Sasha, traveled with her -- showed respect for Chinese traditions and deftly weaved in diplomacy with lighter moments in a way that made the Chinese want to see what she was doing and where she was going.
"Chinese do not only see this leader to leader. They see it family to family and in a broader context the respect of the two great countries," he said. "This is why people got so excited."
Social media, which has exploded in China, likely contributed to the enormous number of page views Obama's visit garnered.
The messaging app WeChat had 355 million monthly users at the end of 2013, according to Forbes, a rousing success for a service that debuted two years earlier. Weibo, the country's popular microblogging site, also has millions of users.
"You have things constantly getting hits," Cheng said. "This tells us it's a rapidly changing country. Sometimes a popular thing can go very, very fast."