To me, "sitting on" implies a lack of use, and revenue these investments and other assets are employed to offset expenses, and, even then, only to a small extent compared to the total expenses. Most of the revenue is donations.
It's unclear from IRS filings what portion of those assets are actually employed in the business operations, but I think that our difference is in what is meant by "sitting on" them. I wouldn't say that a business that owns employee desks is just "sitting on" those assets. The chairs, however.... ;-)
So about 35% of their total assets is either cash or public-traded securities.
While stocks and bonds are not cash, they are pretty liquid in my opinion. They could be sold at market value within an hour.
$35mm in publicly traded securities is not cash-poor by any stretch of the imagination.
That's a lot of liquidity.
When the Wall Street Journal says "Apple's cash pile is now $65.8B" they are talking about $16B of cash, and almost $50B of publicly traded securities.