I'm reading Cryptography And Network Security of William Stallings.
In the SHA-512 section it is said that there is a 512-bit buffer is used to hold the intermediate and final result and every 64-bit obtained somehow (obtained by taking the first sixty-four bits of the fractional parts of the square roots of the first eight prime numbers).
However, if I convert the first of the binary digits to base 10 I get:
a = 7640891576956012808
I searched the square root of 2 in high precision( https://apod.nasa.gov/htmltest/gifcity/sqrt2.1mil ) and did not match. Why?