391616640 has 256 divisors, whose sum is σ = 1405641600. Its totient is φ = 103034880.

The previous prime is 391616623. The next prime is 391616713. The reversal of 391616640 is 46616193.

391616640 is a `hidden beast` number, since 3 + 9 + 1 + 6 + 1 + 6 + 640 = 666.

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 = 391616595 and 391616604.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 2263594 + ... + 2263766.

Almost surely, 2^391616640 is an apocalyptic number.

391616640 is a gapful number since it is divisible by the number (30) 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 391616640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (702820800).

391616640 is an abundant number, since it is smaller than the sum of its proper divisors (1014024960).

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

391616640 is a wasteful number, since it uses less digits than its factorization.

391616640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 332 (or 314 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 391616640 is about 19789.3062030987. The cubic root of 391616640 is about 731.6224874145.

The spelling of 391616640 in words is "three hundred ninety-one million, six hundred sixteen thousand, six hundred forty".