Bernie Sanders a billionaire? That would be a shock.

But Bernie Sanders a millionaire? Sure. And in today’s America, he’s got a lot of company.

Sanders, who acknowledged his seven-digit status last week, is one of an estimated 17.3 million millionaires living in the U.S., by one measure at least.

He’s also a self-described democratic socialist who has placed income distribution and inequality at the center of his two presidential runs. He has said the country is owned and controlled by a small number of billionaires whose greed has torn the fabric of society and because of them, the U.S. is becoming an oligarchy.

That kind of populist rhetoric can make the 77-year-old senator’s perch in the top 5 percent of wealth in America feel a bit, well, awkward.

In any event, that the U.S. is home to more millionaires than ever makes sense. A big wave of baby boomers, many with 401(k)s and perhaps even pension plans, has been moving into retirement after enjoying a decade-long bull market. Before last December’s market rout, Fidelity Investments reported having 187,400 401(k) accounts with balances of $1 million or more, a record high.

That, though, represents only about 1 percent of all Fidelity accounts. Most Americans are far from achieving what Sanders has. Only about 55 percent have 401(k) retirement-savings plans. And four in 10 adults faced with a $400 emergency expense would have to borrow, sell something or not be able to cover it, according to a 2018 report by the Federal Reserve.

Sanders’s rise from a lower-middle-income family, with parents who didn’t go to college, used to be a classic American not-quite-rags to riches story. Statistics show it is is becoming harder to write.

A report by The Pell Institute and PennAhead found that 24-year-olds who grew up in households with at least $116,500 in annual income represented more than half of the college degrees earned in 2014; households with incomes below $35,000 produced just 10 percent of the graduates.

Until a few years ago, Sanders’ net worth was likely below the $1 million mark. Financial-disclosure forms for politicians allow for wide ranges in asset values, making it hard to get a good grasp on how wealthy he is. But in 2015, Sanders clocked in at No. 77 of the 100 senators in terms of net worth, within the range of $271,033 to $1,153,999, according to the Center for Responsive Politics. The group estimated Sanders’ net worth at $712,516.

And he does have debt: His two mortgages are at minimum $350,000 and could be as much as $750,000.

He lamented his relative poverty in a 2016 debate, saying, “Unfortunately, I remain one of the poorer members of the United States Senate.”

This could still be true. An analysis by the Center for Responsive Politics found that more than 70 percent of Senators were millionaires in 2015, the most recent year for the center’s analysis. The median net worth of Republicans in the chamber was $3.3 million, up 13 percent from the previous year, while the median net worth of Democrats was just under $3 million, up 9.6 percent.

Sanders, who isn’t affiliated with either party, has the publishing industry to thank for much of his windfall. He’s penned four books, the latest “Where We Go From Here” in 2018. He earned more than $1 million in 2016, when he got $840,000 in royalties on top of his $174,000 Senate salary. His 2017 financial-disclosure report listed royalties of about $856,000.

Not counted in Sanders’ wealth tally are three homes: two in Vermont and a row house on Capitol Hill in Washington. In 2016, he caught some flak for buying a vacation home — a four-bedroom place on Lake Champlain that cost $575,000. His wife, Jane, said at the time the couple had sold a Maine lake home her family had owned since 1900 and used those proceeds to buy the vacation property.

Sanders has said he will release 10 years of his tax returns by Monday, this year’s deadline for filing.

Now, not everyone’s definition of what qualifies someone as a millionaire is the same. One report’s millionaire may be another’s merely — the horror! — mass affluent.

Some researchers, such as Credit Suisse with its 17.3 million, include housing in the total and subtract debt. Others, including Spectrem Group, don’t include the value of a home. Spectrem figures there were 10.2 million U.S. households in 2018 with a net worth of between $1 million and $5 million, a 2.5 percent rise from 2017. When households with more than $5 million are added in, the tally rises to 11.8 million households with a net worth of at least $1 million.

Sanders had advice for Americans who want to join him in the upper ranks . “I wrote a best-selling book,” he told the New York Times. “If you write a best-selling book, you can be a millionaire, too.”