It is deceitful the way they do it. They mention The Watchtower as the magazine with the largest circulation of 45 million without including the study edition.
In the article on jw.org about their printing operations they mention the 16-page magazine but make no mention of the 32 page editions. They say they produced over 1.3 billion magazines in 2012, thus over 108 million per month, if you subtract the 16 page w and g that leaves over 17 million for the 32 page editions.
Yes, if a non-witness reader bothers to look and see that the magazine is published semi- monthly he or she would wonder where the other issue is, why are they receiving only one issue each month.