Company's iBooks Author application is also popular, tallying 90,000 downloads so far, according to a report from Global Equities Research.
Since digital textbooks are still in their infancy, it might be tough to determine success in that market just yet. But so far, it appears Apple is doing quite well.
The iPhone maker reportedly sold 350,000 digital textbooks through its iBookstore in just its first three days of availability, Global Equities Research has revealed, according to All Things Digital, which obtained the data from the analyst firm. Global Equities Research monitors textbook downloads through its own "proprietary tracking system," All Things Digital said today. The firm doesn't disclose how that system works.
Last week, Apple unveiled digital textbooks for its iPad. The books, which are coming through major textbook publishers McGraw-Hill and Pearson, among others, allow for far more interactivity than physical editions. The textbooks come with video, 3D images, instant glossaries, and the ability to highlight and add notes. In addition, Apple is charging $14.99 or less for the high school textbooks available so far, making them more affordable than their traditional counterparts.
According to All Things Digital, citing Global Equities Research's data, that price won't necessarily hurt textbook publishers, which are accustomed to a typical markup on textbooks of between 33 and 35 percent, due to the number of parties that handle books throughout the supply chain to get them into classrooms. With Apple's direct-to-consumer option, the middleman and production costs are cut out of the equation, allowing publishers to sell textbooks at a discount.
Moving away from the books themselves, Apple also unveiled iBooks Author at last week's event. That Mac OS X-based application is designed to make it easier for authors to publish interactive iBooks and textbooks. According to Global Equities Research, iBooks Author was downloaded 90,000 times during its first three days of availability, indicating that authors have designs on self-publishing books in the coming months.
For its part, Apple hasn't divulged download figures. The company did not immediately respond to CNET's request for comment on the Global Equities Research findings.