More than 4.2 million people worldwide bought PlayStation 4s in 2013, and more than half of those PS4 owners have signed up for a PlayStation Plus subscription, said Sony CEO Kazuo Hirai in an investor call last week.

"All the 4.2 million PS4s that have already moved into the hands of consumers, more than half of the people that have now gotten their hands [on] the PS4 have actually signed up for PS Plus service, which bodes very well for us," said Hirai in a conference call to discuss the earnings for the third quarter of Sony's 2014 fiscal year, according to a transcript from Seeking Alpha.

It's unclear if that figure takes into account any PS4 owner who redeemed the 30-day PS Plus trial that comes with the console, or if Hirai was referring only to PlayStation Network users who have signed up for a paid subscription. Sony charges $49.99 for one year, $17.99 for three months and $9.99 for one month of PS Plus service. We've reached out to the company for clarification, and will update this article with any information we receive.

During the conference call, Sony said it still expects to sell a combined 15 million units of the PlayStation 3 and PS4 by the end of March. While the PS4 is selling better than Sony anticipated, PS4 sales are being offset by weaker-than-expected sales of the PS3. The PS4 is available in numerous regions around the world, but has not yet been released in Japan; it will launch there on Feb. 22.