391688 has 16 divisors (see below), whose sum is σ = 801360. Its totient is φ = 178000.

The previous prime is 391679. The next prime is 391691. The reversal of 391688 is 886193.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 391688.

It is an unprimeable number.

391688 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2138 + ... + 2313.

It is an arithmetic number, because the mean of its divisors is an integer number (50085).

2³⁹¹⁶⁸⁸ is an apocalyptic number.

It is an amenable number.

391688 is an abundant number, since it is smaller than the sum of its proper divisors (409672).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

391688 is a wasteful number, since it uses less digits than its factorization.

391688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4468 (or 4464 counting only the distinct ones).

The product of its digits is 10368, while the sum is 35.

The square root of 391688 is about 625.8498222417. The cubic root of 391688 is about 73.1666923226.

It can be divided in two parts, 3916 and 88, that added together give a palindrome (4004).

The spelling of 391688 in words is "three hundred ninety-one thousand, six hundred eighty-eight".