Don't have a lot of time to follow stocks and want some safe options for your portfolio? Three stocks that are big names within their respective industries and that can make for excellent long-term investments are UnitedHealth Group (UNH 0.30%), Coca-Cola (KO), and Oracle (ORCL 2.02%). These businesses have excellent track records, they pay their shareholders dividends, and their futures remain bright.

1. UnitedHealth Group

Healthcare and insurance are two relatively safe places of the economy for investors to focus on. There's an ongoing need for both of those services and one company that gives you the best of both worlds is health insurance giant UnitedHealth Group. It has also made for a fantastic growth stock, having doubled in a span of just five years.

At a market capitalization of around $500 billion, it's one of the most valuable healthcare companies in the world. The company doesn't have the greatest bottom line as it has averaged a profit margin of just 6% over the trailing 12 months. But UnitedHealth generates over $300 billion in revenue on an annual basis, which means that at a 6% margin, it can still generate more than $18 billion in profit each year. Over the past four quarters, its earnings have been higher than that, at $21.7 billion.

UnitedHealth is also always on the hunt to get bigger. Earlier this year, the company announced plans to acquire home health company Amedisys for $3.3 billion. That builds off its $5.4 billion acquisition of another home health business, LHC Group. With a plethora of profits and cash coming through its business, UnitedHealth is in excellent shape to continue growing and expanding via acquisitions in the long run.

Investors also have plenty of incentive to hold on to the stock as UnitedHealth pays a dividend that yields 1.4%. And while that may seem modest, it's deceptively low as the company has an excellent track record for dividend growth.

UnitedHealth is one of the safest healthcare stocks investors can own, and it's a no-brainer if you want an investment that you don't want to worry about.

2. Coca-Cola

Soft drink giant Coca-Cola doesn't need much of an introduction. Go into any grocery store or restaurant within the country and there's a good chance you'll find one of its products either being served or available for purchase. The simplicity of its business is what makes it appealing to long-term investors such as Warren Buffett; Coca-Cola is among the top holdings in Berkshire Hathaway's portfolio.

Coca-Cola earns great margins on its products. In the past 12 months, the company's profit margin has been just under one-quarter of the top line. The business has been resilient, even in the midst of rising costs. Its low-priced products make it easier for Coca-Cola to raise prices without making them appear too expensive.

The company has been able to adapt to changing consumer trends over the years, such as launching healthier products and drinks with no sugar. That ability to evolve is an important one for long-term investors to consider, which is why the business is a solid one to hang on to for years.

Coca-Cola also pays a dividend that currently yields 3.1%. And the stock is a Dividend King, making it highly probable that the dividend income you earn from the stock will increase over time.

3. Oracle

Another big name for investors to consider is Oracle. The brand has become synonymous with databases but it's also much more than that. These days, it's also focusing on the rising popularity of artificial intelligence (AI). Chief Technology Officer and Chairman Larry Ellison stated earlier this year that the company was spending billions of dollars on AI chips from Nvidia as it aims to grow its cloud computing business.

Oracle's strong profit margins in excess of 18% put it in a great position to pump more money into AI so that it can take advantage of what's proving to be a hot trend not just in tech, but in other industries as well, with companies looking for ways to make their operations more efficient. The company pays a dividend yield of 1.4% but it's not getting in the way of growth; Oracle's payout ratio is around 43% of profits. That leaves plenty of room for the company to invest back into its growth opportunities.

Shares of Oracle are up more than 40% this year, but with a forward price-to-earnings multiple of just over 20, the stock is trading in line with the S&P 500 average. Oracle is a top tech company to invest in and as it expands its AI capabilities, there can be a lot more growth on the horizon.