391904838 has 64 divisors (see below), whose sum is σ = 959777280. Its totient is φ = 117772704.

The previous prime is 391904827. The next prime is 391904839. The reversal of 391904838 is 838409193.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 391904793 and 391904802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391904839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 23695 + ... + 36677.

It is an arithmetic number, because the mean of its divisors is an integer number (14996520).

Almost surely, 2^391904838 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 391904838, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (479888640).

391904838 is an abundant number, since it is smaller than the sum of its proper divisors (567872442).

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

391904838 is a wasteful number, since it uses less digits than its factorization.

391904838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13050 (or 13044 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The square root of 391904838 is about 19796.5865239440. The cubic root of 391904838 is about 731.8019149583.

The spelling of 391904838 in words is "three hundred ninety-one million, nine hundred four thousand, eight hundred thirty-eight".