Wikipedia helpful explains:
The number 2,147,483,647 (two billion one hundred forty-seven million four hundred eighty-three thousand six hundred forty-seven) is the eighth Mersenne prime, equal to 231 − 1. It is one of only four known double Mersenne primes…The number 2,147,483,647 may have remained the largest known prime until 1867.
The number 2,147,483,647 is also the maximum value for a 32-bit signed integer in computing. It is therefore the maximum value for variables declared as
int in many programming languages running on popular computers, and the maximum possible score, money etc. for many video games. The appearance of the number often reflects an error,overflow condition, or missing value.
The data type time_t, used on operating systems such as Unix, is a 32-bit signed integer counting the number of seconds since the start of the Unix epoch (midnight UTC of 1 January 1970). The latest time that can be represented this way is 03:14:07 UTC on Tuesday, 19 January 2038 (corresponding to 2,147,483,647 seconds since the start of the epoch), so that systems using a 32-bit
time_t type are susceptible to the Year 2038 problem.