The honest answer: As many as you'd like. But here's what some popular authors have been doing:
Holes by Louis Sachar - This 47,000 word novel spanned 50 chapters and averaged only 940 words per chapter.
The Graveyard Book by Neil Gaiman - At 67,380 words and 10 chapters, Neil Gaiman averaged 6,738 words per chapter.
Harry Potter and the Sorcerer's Stone by J.K. Rowling - Rowling squeezed 77,508 words into 17 chapters for 4,559 words per chapter.
Stardust by Neil Gaiman - 59,000 words in 10 chapters and an epilogue. Roughly 5,900 words per chapter.
The Hunger Games by Suzanne Collins - 99,750 words divided into 27 chapters. Collins averaged nearly 3,700 words per chapter.
Scepter of the Ancients by Derek Landy - With 30 chapters and 67,424 words, Landy averaged 2,247 words per chapter.
Here's one thing I have noticed. Regardless of word count, long chapters make a book feel long. Short chapters make a book feel short.