391128 has 32 divisors (see below), whose sum is σ = 1003200. Its totient is φ = 127008.

The previous prime is 391117. The next prime is 391133. The reversal of 391128 is 821193.

It is a super-2 number, since 2×391128² = 305962224768, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a junction number, because it is equal to n+sod(n) for n = 391098 and 391107.

It is a congruent number.

It is an unprimeable number.

391128 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 7 ways as a sum of consecutive naturals, for example, 843 + ... + 1221.

It is an arithmetic number, because the mean of its divisors is an integer number (31350).

2³⁹¹¹²⁸ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 391128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (501600).

391128 is an abundant number, since it is smaller than the sum of its proper divisors (612072).

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

391128 is a wasteful number, since it uses less digits than its factorization.

391128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 431 (or 427 counting only the distinct ones).

The product of its digits is 432, while the sum is 24.

The square root of 391128 is about 625.4022705427. The cubic root of 391128 is about 73.1318066569.

The spelling of 391128 in words is "three hundred ninety-one thousand, one hundred twenty-eight".