391281920 has 144 divisors (see below), whose sum is σ = 988968960. Its totient is φ = 148119552.

The previous prime is 391281899. The next prime is 391281929. The reversal of 391281920 is 29182193.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391281929) 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 15 ways as a sum of consecutive naturals, for example, 3080897 + ... + 3081023.

It is an arithmetic number, because the mean of its divisors is an integer number (6867840).

Almost surely, 2^391281920 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 391281920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (494484480).

391281920 is an abundant number, since it is smaller than the sum of its proper divisors (597687040).

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

391281920 is a wasteful number, since it uses less digits than its factorization.

391281920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260 (or 246 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 391281920 is about 19780.8473023781. The cubic root of 391281920 is about 731.4139854792.

The spelling of 391281920 in words is "three hundred ninety-one million, two hundred eighty-one thousand, nine hundred twenty".