391949856 has 72 divisors (see below), whose sum is σ = 1120981680. Its totient is φ = 129902976.

The previous prime is 391949849. The next prime is 391949869. The reversal of 391949856 is 658949193.

It is a tau number, because it is divible by the number of its divisors (72).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 47751 + ... + 55353.

It is an arithmetic number, because the mean of its divisors is an integer number (15569190).

Almost surely, 2^391949856 is an apocalyptic number.

391949856 is a gapful number since it is divisible by the number (36) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 391949856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (560490840).

391949856 is an abundant number, since it is smaller than the sum of its proper divisors (729031824).

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

391949856 is a wasteful number, since it uses less digits than its factorization.

391949856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7798 (or 7787 counting only the distinct ones).

The product of its digits is 2099520, while the sum is 54.

The square root of 391949856 is about 19797.7235054943. The cubic root of 391949856 is about 731.8299345131.

The spelling of 391949856 in words is "three hundred ninety-one million, nine hundred forty-nine thousand, eight hundred fifty-six".