Apple reported $44 in earnings over the last 4 quarters. The current stock price is $400 and they have $140 billion in cash on hand. They pay approximately a 1% dividend, maybe a hair more, maybe as much as 1.5% dividend yield at this depressed price, but let's just say 1%.
Therefore TTM P/E is 6; for a back of the envelope calculation, I like to subtract a point from that for every % of dividend yield, in terms of comparison to other stocks that don't pay dividends, and prior periods when the dividend yield was 0% or different.
It is not often that you get to buy AAPL in the 4.5-5 adjusted P/E range. The market is either saying that AAPL is a huge value trap or non-rational methods of valuation are being used by market participants. I believe the latter.