There’s a reason why Richard B. Cohen escapes attention.

The chairman of C&S Wholesale Grocers Inc. works out of a nondescript office park once slated to house a county jail in Keene, New Hampshire, a leafy mountain hamlet 90 miles northwest of Boston.

The truckers who deliver goods from the company’s 54 distribution centers drive unmarked tractor-trailers. Cohen’s last interview was published a decade ago. Even the Keene Chamber of Commerce overlooked C&S as one of the town’s largest employers.

“We’re the biggest company no one has ever heard of,” Bryan T. Granger, a company spokesman, said by phone.

The 61-year-old — who goes by “Rick” — has transformed C&S into the world’s largest grocery wholesaler since taking the helm of the business in 1989, making him one of the 100 richest people in the world and the wealthiest man in New England after Connecticut hedge-fund manager Raymond T. Dalio, according to the Bloomberg Billionaires Index.

The company had sales of $21.7 billion in 2012, distributing more than 95,000 products to 4,000 supermarkets from Maine to Hawaii. Cohen is the business’ sole owner, Granger said. He has a net worth of $11.2 billion, according to the Bloomberg index, and has never appeared on an international wealth ranking — a status one associate said suits him just fine.

‘Smart, Analytic’

“I tried to put our name on the trucks and he didn’t want any part of it,” said Edward Albertian, 58, a former C&S president and now chief executive officer of Citysports, a 22-store Boston-based retailer owned by Highland Capital Partners LP. “He wanted to continue to be stealth and operate in this little, dinky Keene, New Hampshire, marketplace.”

The billionaire has managed to make money in an industry bedeviled by small profit margins and mismanagement by focusing on efficiency and paying his workers extra to avoid mistakes, according to Thomas DeLong, a professor at Harvard Business School who consults with Cohen and wrote a case study on the company published in 2003.

“I’m not sure I’ve met anyone as smart, analytic and quantitatively driven as Rick,” DeLong said in a telephone interview. “Many CEOs have a need to prove they’re the smartest guy in the room. Rick is not like that.”