BISHOP, Texas - The odds that Joan Ginther would hit four Texas Lottery jackpots for a combined nearly $21 million are astronomical. Mathematicians say the chances are as slim as 1 in 18 septillion - that's 18 and 24 zeros.

Just as unlikely? Getting to know one of the luckiest women in the world.

"She wants her privacy," friend Cris Carmona said.

On a $50 scratch-off ticket bought in this rural farming community, Ginther won $10 million last month in her biggest windfall yet. But it was the fourth winning ticket in Texas for the 63-year-old former college professor since 1993, when Ginther split an $11 million jackpot and became the most famous native in Bishop history.

But she's a celebrity who few in this town of 3,300 people can say much about.

At the Times Market where Ginther bought her last two winning tickets, the highway gas station is fast becoming a pilgrimage for unlucky lottery losers. Lines stretch deep past a $5.98 bin of Mexican movie DVDs, and a woman from Rhode Island called last week asking to buy tickets from the charmed store through the mail.

She was told that was illegal. The woman called back to plead again anyway.

The Texas Lottery Commission has seen repeat winners before, but none on the scale of Ginther. Spokesman Bobby Heith said the agency has never investigated Ginther's winnings - three scratch-off tickets and one lottery draw - for possible fraud but described the verification system as thorough. Her other winnings - both from scratch-off tickets - were $2 million in 2006 and $3 million in 2008.

Ginther has never spoken publicly about her lotto winnings and could not be found for comment. She now lives in Las Vegas after moving away from Bishop, and an answering machine message for a telephone number listed at her address says not to leave a message.

She asked the few people who've exchanged more than brief pleasantries with her not to grant interviews and sneaked into lottery headquarters in Austin to collect her winnings with the least publicity the state offers jackpot winners.

Calculating the actual odds of Ginther hitting four multimillion-dollar lottery jackpots is tricky. If Ginther's winning tickets were the only four she ever bought, the odds would be one in 18 septillion, according to Sandy Norman and Eduardo Duenez, math professors at the University of Texas at San Antonio.

Exactly how often Ginther plays is unknown. But Norman and Duenez said that a habitual player winning four times over a 17-year span is much less far-fetched.