That seems extremely high to me. Also, iPads bring in less revenue per unit sold (13.170 million sold for $5.862 billion of revenue, or $445 per iPad)
What do they count in iPhone revenue? “deferrals and amortization of related software upgrade rights and non-software services.” according to https://www.apple.com/newsroom/pdfs/Q1_FY18_Data_Summary.pdf, but what are those, and why would they be different for iPhones vs iPads?