There are a few factors that make the "ideal" dividend stock. A high yield is the obvious one, but dividend safety and long-term growth potential are important, as well. One dividend stock that checks all of the boxes is Iron Mountain (IRM 0.54%), a records and data storage company that operates as a real estate investment trust, or REIT.

What does Iron Mountain do?

Iron Mountain is a leader in records storage and information management, operating in 1,455 facilities located in 47 countries around the world, with a total of 87 million square feet of space. Just to give you an idea of the scale of Iron Mountain's operations, the company stores 682 million cubic feet of hardcopy records, 89 million pieces of media, and one billion medical images. Ninety-five percent of the Fortune 1000 are Iron Mountain customers, and the overall client list has more than 230,000 customers on it.

Boxes of papers in storage.

Iron Mountain is a leader in secure document storage. Image Source: Getty Images. (Note: Image doesn't necessarily depict an Iron Mountain facility.)

As mentioned, records and information management is Iron Mountain's primary business. This makes up 75% of the company's total revenue. Data storage and service make up another 15%, and Iron Mountain's document-shredding service contributes the other 10%.

Strong recent results and excellent projected growth

In its second-quarter earnings report, Iron Mountain showed some impressive growth. Revenue grew 8.4% year over year, and normalized FFO (funds from operations) grew to $0.55 per share from $0.48 a year ago.

From 2013-2017, Iron Mountain has been growing its revenue at an 8.3% annualized rate (based on 2017 guidance). Going forward, Iron Mountain is targeting 8% adjusted earnings before interest, taxes, depreciation, and amortization (EBITDA) growth, which it expects will produce 9% annualized adjusted FFO growth, as well as a dividend growth rate in excess of 4% per year.

Why is Iron Mountain a dividend investor's dream?

Iron Mountain's business is attractive because it combines several advantages of other types of real estate. Specifically, Iron Mountain benefits from the low-cost advantages of storage facilities (low maintenance and operating expenses), but without the downside of a month-to-month lease structure. Iron Mountain's average lease has a three-year term, and the average item stored by the company has been there for 15 years. In other words, Iron Mountain has low expenses and strong tenant retention -- a rare combination, especially in storage-oriented businesses.

Iron Mountain's retention rate.

Image Source: Iron Mountain investor presentation.

The economics of Iron Mountain's business are highly attractive. In Iron Mountain's North American storage facilities, the company invests an average of $161 per square foot, including the building itself, furniture and equipment, and customer-acquisition costs. The space generates a stabilized net interest income of $22 per square foot, resulting in an extremely lucrative 14% return on invested capital.

Iron Mountain projects that, in North America alone, there's an approximately 720 million cubic-foot growth opportunity for the records-storage business, and is expecting the need for data storage and management to grow exponentially in the coming years. This is in addition to the massive growth opportunity the company sees in emerging markets. In the 2018-2020 period, Iron Mountain projects $450 million-$600 million in business acquisitions, about $500 million in data-center development and real estate consolidation, as well as up to $100 million in investments into its adjacent businesses.

In fact, along with its second-quarter earnings report, Iron Mountain announced that it has agreed to acquire MAG DATACENTERS, a data-center business, for $128 million, adding over 9 megawatts of data-center capacity to Iron Mountain's operations.

Is the dividend safe?

Based on Iron Mountain's stock price as of this writing, the company's $2.20 annual dividend translates to a 6.3% yield. This may sound high, but it represents less than 80% of the company's expected AFFO (adjusted earnings from operations) for 2017 -- a very reasonable payout for a REIT.

In addition, I mentioned that the company is projecting a dividend-growth rate of at least 4% annualized going forward. Iron Mountain expects a minimum dividend of $2.54 for 2020.

In a nutshell, Iron Mountain not only pays a high dividend, but the dividend is pretty safe. Not only that, but management is prioritizing dividend growth going forward, so Iron Mountain could be a reliable and growing income stream in your portfolio.

The Foolish bottom line

No stock that pays a 6.3% dividend and is capable of double-digit total returns is without risk, and Iron Mountain is not an exception. However, in this case, I feel that the long-term reward potential greatly exceeds the risk, which makes Iron Mountain an excellent investment for dividend investors with a long time horizon.