312391 has 4 divisors (see below), whose sum is σ = 320872. Its totient is φ = 303912.

The previous prime is 312383. The next prime is 312397. The reversal of 312391 is 193213.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 193213 = 101 ⋅1913.

It is a cyclic number.

It is not a de Polignac number, because 312391 - 2³ = 312383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (312397) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4185 + ... + 4258.

It is an arithmetic number, because the mean of its divisors is an integer number (80218).

2³¹²³⁹¹ is an apocalyptic number.

312391 is a deficient number, since it is larger than the sum of its proper divisors (8481).

312391 is an equidigital number, since it uses as much as digits as its factorization.

312391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8480.

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

The square root of 312391 is about 558.9194933083. The cubic root of 312391 is about 67.8525495902.

It can be divided in two parts, 312 and 391, that added together give a triangular number (703 = T₃₇).

The spelling of 312391 in words is "three hundred twelve thousand, three hundred ninety-one".