399445664 has 48 divisors (see below), whose sum is σ = 854542080. Its totient is φ = 183098880.

The previous prime is 399445663. The next prime is 399445693. The reversal of 399445664 is 466544993.

It is not an unprimeable number, because it can be changed into a prime (399445663) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8252 + ... + 29444.

It is an arithmetic number, because the mean of its divisors is an integer number (17802960).

Almost surely, 2^399445664 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 399445664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (427271040).

399445664 is an abundant number, since it is smaller than the sum of its proper divisors (455096416).

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

399445664 is a wasteful number, since it uses less digits than its factorization.

399445664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21253 (or 21245 counting only the distinct ones).

The product of its digits is 2799360, while the sum is 50.

The square root of 399445664 is about 19986.1367952889. The cubic root of 399445664 is about 736.4657771622.

The spelling of 399445664 in words is "three hundred ninety-nine million, four hundred forty-five thousand, six hundred sixty-four".