256 according to the publisher (see related link.)
Queen of Demons has 479 pages.
Demons of Chitrakut has 628 pages.
Demons by Daylight has 153 pages.
Europe's Inner Demons has 302 pages.
Demons Don't Dream has 304 pages.
There are 3 books and a comic book and a mangaThe Dangerous Days of Daniel XDaniel X: Alien Hunter (Daniel X, #1.5)Daniel X: Watch the Skies (Daniel X, #2)Daniel X: Demons and Druids (Daniel X, #3)Daniel X: The Manga, Vol. 1
Daniel's Story has 131 pages.
Daniel Martin - novel - has 704 pages.
Moscow Rules - Daniel Silva novel - has 433 pages.
The Dangerous Days of Daniel X has 238 pages.
The first Vampirates book, "Vampirates: Demons of the Ocean" by Justin Somper, is approximately 336 pages long.
"Shattered Peace" by Daniel Yergin has approximately 576 pages.