Of the more than 1,645 billionaires on the latest Forbes list, only 172 are women. And only 32 of them are self-made, the rest having made their money from marriage or inheritance.
Why aren't there more, given the strides women have made in the rest of the economy? And do men and women create wealth differently?
A new study from Spectrem Group suggests that when it comes to creating wealth, women have a different experience and perspective than men. The survey asked men and women millionaires about the factors that led to their wealth.
Women were more likely to cite frugality, family connections and financial advice, while men were talked more about luck, risk-taking and running their own business.
According to the survey, 84 percent of women millionaires cited frugality as a factor in obtaining their wealth compared with 78 percent of men. Forty-six percent of women cited "decisions made for me by financial advisors" (versus 34 percent for men) and 11 percent cited "family connections" compared with only 7 percent for men.
(Read more: How many women millionaires? Depends on the study)
Of the men surveyed, 40 percent cited "luck" compared with 34 percent of women. Nearly two-thirds, 64 percent, cited "taking risk" (versus 51 percent for women) and 21 percent of men cited "running my own business," (versus 17 percent for women).
George Walper, president of Spectrem Group, the wealth research firm, said that women face different obstacles—and therefore credit their wealth to different factors.
"Because of the unique financial challenges women face, such as salary inequality, that can impact retirement savings, they are more likely than men to credit frugality," he said. "Men, on the other hand, are generally less risk-averse and more aggressive investors than women and more likely to pat themselves on the back for risk taking."
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He added that women are more willing to credit their financial advisors for good advice compared to men, who may be more likely to credit themselves for investment decisions.
—CNBC's Robert Frank. Follow him on Twitter @robtfrank.