Investing in mutual funds for retirement is never too late. And the Zacks Mutual Fund Rank can be an excellent tool for investors looking to invest in the best funds.

How can you tell a good mutual fund from a bad one? It's pretty basic: if the fund is diversified, has low fees, and shows strong performance, it's a keeper. Of course, there's a wide range, but using the Zacks Mutual Fund Rank, we've found three mutual funds that would be great additions to any long-term retirement investors' portfolios.

Here are the funds that have achieved the Zacks Mutual Fund Rank #1 (Strong Buy) and have low fees.

If you are looking to diversify your portfolio, consider VY T. Rowe Price Diversified Mid Cap Growth S2 (IAXTX Quick QuoteIAXTX - Free Report) . IAXTX is a Mid Cap Growth mutual fund. These mutual funds choose companies with a stock market valuation between $2 billion and $10 billion. This fund is a winner, boasting an expense ratio of 1.17%, management fee of 0.74%, and a five-year annualized return track record of 11.27%.

Victory Diversified Stock R6 (VDSRX Quick QuoteVDSRX - Free Report) : 0.78% expense ratio and 0.65% management fee. VDSRX is a Large Cap Blend fund, targeting companies with market caps of over $10 billion. These funds offer investors a stability, and are perfect for people with a "buy and hold" mindset. VDSRX, with annual returns of 14.7% over the last five years, is a well-diversified fund with a long track record of success.

Fidelity Advisor International Growth Z (FZAJX Quick QuoteFZAJX - Free Report) : 0.79% expense ratio and 0.71% management fee. FZAJX is a Non US - Equity option, focusing their investments acoss emerging and developed markets, and can often extend across cap levels too. With a five-year annual return of 9.94%, this fund is a well-diversified fund with a long track record of success.

There you have it. If your financial advisor had you put your money into any of our top-ranked funds, then they've got you covered. If not, you may need to talk.