123391 has 4 divisors (see below), whose sum is σ = 124312. Its totient is φ = 122472.

The previous prime is 123379. The next prime is 123397. The reversal of 123391 is 193321.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 193321 = 97 ⋅1993.

It is a cyclic number.

It is not a de Polignac number, because 123391 - 2¹¹ = 121343 is a prime.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (123397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 216 + ... + 541.

It is an arithmetic number, because the mean of its divisors is an integer number (31078).

2¹²³³⁹¹ is an apocalyptic number.

123391 is a deficient number, since it is larger than the sum of its proper divisors (921).

123391 is an equidigital number, since it uses as much as digits as its factorization.

123391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 920.

The product of its digits is 162, while the sum is 19.

The square root of 123391 is about 351.2705510002. The cubic root of 123391 is about 49.7845395361.

It can be divided in two parts, 12 and 3391, that added together give a triangular number (3403 = T₈₂).

The spelling of 123391 in words is "one hundred twenty-three thousand, three hundred ninety-one".