Stock investors today face data overload.

Aside from basic financial statements, there is a flood of ratios, statistics, multiples, analyst estimates, comps, margins, and industry-specific metrics to wade through.

In this regular series, I will choose a company and distill all the data down to three numbers you absolutely need to know before making a buy-sell-ignore decision.

Today's breakdown is for Sirius XM (Nasdaq: SIRI), the satellite radio provider that's home to Howard Stern and millions of loyal listeners.

$3.4 billion
Sirius has a net debt load position of $3.4 billion. When compared to its market capitalization of $3.9 billion, that's a lot. Especially for a company that relies on consumers' discretionary income. And it's not like Sirius is pumping out the cash to service the debt -- that $3.4 billion is more than 60 times its 12-month trailing free cash flow.

A red flag, for sure.

19.5 million
A more favorable stat for Sirius is its 19.5 million subscriber count. The satellite television providers bookend its count with 23.1 million for DirecTV (Nasdaq: DTV) and 14.1 million for Dish Network (Nasdaq: DISH). And for all the hype about Netflix's (Nasdaq: NFLX) DVD subscription service dominance, it has just north of 13 million subs -- millions behind Sirius.

Not too shabby, Sirius.

$11.48
At this point, you may be wondering how Sirius has so many subscribers but an anemic free cash flow and perilous debt position. The answer is its $11.48 average revenue per user (ARPU). Each month, Sirius takes in $11.48 per sub. Compare that to DirecTV's U.S. figure: $85.47.

In other words, consumers are spending more than seven times as much for DirecTV's satellite TV service as they are Sirius's satellite radio service.

With consumers unwilling to pay up for premium radio, Sirius needs to make it up on customer retention, cost cutting, and volume.

As you decide whether to buy, sell, or ignore Sirius XM, keep these three numbers top of mind.