391220720 has 40 divisors (see below), whose sum is σ = 992280240. Its totient is φ = 142261760.

The previous prime is 391220717. The next prime is 391220737. The reversal of 391220720 is 27022193.

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 391220720.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 221405 + ... + 223164.

It is an arithmetic number, because the mean of its divisors is an integer number (24807006).

Almost surely, 2^391220720 is an apocalyptic number.

It is an amenable number.

391220720 is an abundant number, since it is smaller than the sum of its proper divisors (601059520).

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

391220720 is a wasteful number, since it uses less digits than its factorization.

391220720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 444593 (or 444587 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 391220720 is about 19779.3002909607. The cubic root of 391220720 is about 731.3758502562.

The spelling of 391220720 in words is "three hundred ninety-one million, two hundred twenty thousand, seven hundred twenty".