This number is a prime.
The exponent in the 50th known Mersenne prime is a concatenation of two 4-digit primes, 7723 and 2917. These primes have the same prime sum of digits, (19). Note that this is the 2nd case in which the exponent in a Mersenne prime is a concatenation of two primes with the same length. The first such case is the exponent 859433 in the 33rd Mersenne prime. [Loungrides]
The fiftieth Mersenne prime exponent is the first such exponent that starts and ends with the same prime digit. [Loungrides]
The Mersenne prime exponent '77232917' contains a record-breaking eleven prime substrings when read left-to-right, i.e., 2, 3, 7, 17, 23, 29, 2917, 7723, 23291, 32917, 7232917. [Harrison]