A book that recorded the largest prime numbers at the time (numbers that can only be divided by 1 and itself) in small numbers over a total of 838 pages.
Specifically, it is 2^82,589,933-1, a huge number boasting 24,862,048 digits.
This number is the second largest known prime number and the largest prime number is
2^136,279,841 1 is 41,024,320 digits.