391220928 has 140 divisors (see below), whose sum is σ = 1325495952. Its totient is φ = 111767040.

The previous prime is 391220927. The next prime is 391220959. The reversal of 391220928 is 829022193.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 391220892 and 391220901.

It is not an unprimeable number, because it can be changed into a prime (391220927) by changing a digit.

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 19 ways as a sum of consecutive naturals, for example, 30898 + ... + 41678.

Almost surely, 2^391220928 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 391220928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (662747976).

391220928 is an abundant number, since it is smaller than the sum of its proper divisors (934275024).

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

391220928 is a wasteful number, since it uses less digits than its factorization.

391220928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10812 (or 10793 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 391220928 is about 19779.3055489822. The cubic root of 391220928 is about 731.3759798728.

The spelling of 391220928 in words is "three hundred ninety-one million, two hundred twenty thousand, nine hundred twenty-eight".