Dividend investing is a tried-and-true strategy for generating strong, steady returns in economies both good and bad. But as corporate America's slew of dividend cuts and suspensions over the past few years has demonstrated, it's not enough simply to buy a high yield. You also need to make sure those payouts are sustainable.

Let's examine how Aflac (NYSE: AFL) stacks up in four critical areas to determine whether it's a dividend dynamo or a disaster in the making.

1. Yield
First and foremost, dividend investors like a large yield. But if a yield gets too high, it may reflect investors' doubts about the payout's sustainability. If investors had confidence in the stock, they'd be buying it, driving up the share price and shrinking the yield.

Aflac yields 2.5%, modest and certainly not cause for alarm.

2. Payout ratio
The payout ratio might be the most important metric for judging dividend sustainability. It compares the amount of money a company pays out in dividends to the amount it generates. A ratio that's too high -- say, greater than 80% of earnings -- indicates that the company may be stretching to make payouts it can't afford.

Aflac's payout ratio is a conservative 26%.

3. Balance sheet
The best dividend payers have the financial fortitude to fund growth and respond to whatever the economy and competitors throw at them. The interest coverage ratio indicates whether a company is having trouble meeting its interest payments -- any ratio less than five is a warning sign. Meanwhile, the debt-to-equity ratio is a good measure of a company's total debt burden.

Let's examine how Aflac stacks up next to its peers:

Company

Debt-to-Equity Ratio

Interest Coverage Ratio

Aflac

30%

21 times

MetLife (NYSE: MET)

133%

164 times

Prudential Financial (NYSE: PRU)

103%

N/A

Hartford Financial (NYSE: HIG)

33%

6 times

Source: Capital IQ, a division of Standard & Poor's.

Aflac's debt doesn't appear particularly burdensome, especially in relation to that of its peers.

4. Growth
A large dividend is nice; a large growing dividend is even better. To support a growing dividend, we also want to see earnings growth.

Over the past five years, Aflac's earnings per share have grown 8% annually, while its dividend has grown at 20%.

The Foolish bottom line
Assuming no monumental insurance claims, Aflac exhibits a fairly clean dividend bill of health. Its yield appears affordable and quite conservative, leverage seems manageable, and growth is impressive.

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Ilan Moscovitz doesn't own shares of any company mentioned. David Williamson owns no shares of the companies mentioned. The Motley Fool owns shares of Aflac. Motley Fool newsletter services have recommended buying shares of Aflac. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.