391391 has 32 divisors (see below), whose sum is σ = 580608. Its totient is φ = 253440.

The previous prime is 391387. The next prime is 391393. The reversal of 391391 is 193193.

391391 = 4² + 5² + ... + 105².

It is not a de Polignac number, because 391391 - 2² = 391387 is a prime.

It is a Smith number, since the sum of its digits (26) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 391391.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 391391.

It is not an unprimeable number, because it can be changed into a prime (391393) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 17006 + ... + 17028.

It is an arithmetic number, because the mean of its divisors is an integer number (18144).

2³⁹¹³⁹¹ is an apocalyptic number.

391391 is a deficient number, since it is larger than the sum of its proper divisors (189217).

391391 is a wasteful number, since it uses less digits than its factorization.

391391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71.

The product of its digits is 729, while the sum is 26.

The square root of 391391 is about 625.6124998751. The cubic root of 391391 is about 73.1481946047.

It can be divided in two parts, 3913 and 91, that added together give a palindrome (4004).

The spelling of 391391 in words is "three hundred ninety-one thousand, three hundred ninety-one".