If you're looking for dividend income and you're interested in becoming a shareholder in BlackRock (BLK 1.15%) -- the world's largest asset manager, with more than $12 trillion under management -- you might wonder how well it pays to own the stock. For instance, how many shares would you need to buy to collect $1,000 annually?

Here's your answer: 48 shares. It doesn't sound like all that many shares, but there's more to consider when it comes to BlackRock stock.

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First, a review of that dividend math. BlackRock shares recently traded at about $1,100 per share, and the stock's annual dividend payout was $20.84 per share. (Its recent dividend yield was 1.9%.) If you're looking to collect about $1,000 annually, you'd divide that $1K figure by $20.84, getting 47.98. So you'd need 48 shares.

That may not seem like very many shares, but remember that each share has a $1,100 price tag. Those 48 shares would cost you about $52,800.

Note that BlackRock has been raising its payout for 16 years in a row. Over the past five years, the payout increased by an annual average rate of 7.5%. So while the dividend yield isn't massive right now, it is growing at a respectable clip. If it keeps up that rate, you might be collecting $2,000 annually in dividends a decade from now.

The stock's payout ratio -- the percentage of earnings paid out in dividends -- is quite reasonable, too, at less than 50% in the most recent quarter. That leaves plenty of room for further increases.

There's a lot to like about BlackRock, such as revenue growing by double-digit percentages. So take a closer look to see if it's a good fit for your portfolio.