399393840 has 80 divisors (see below), whose sum is σ = 1258464096. Its totient is φ = 104755200.

The previous prime is 399393823. The next prime is 399393881. The reversal of 399393840 is 48393993.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 399393840.

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 15 ways as a sum of consecutive naturals, for example, 1000 + ... + 28280.

Almost surely, 2^399393840 is an apocalyptic number.

399393840 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 399393840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (629232048).

399393840 is an abundant number, since it is smaller than the sum of its proper divisors (859070256).

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

399393840 is a wasteful number, since it uses less digits than its factorization.

399393840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27358 (or 27352 counting only the distinct ones).

The product of its (nonzero) digits is 629856, while the sum is 48.

The square root of 399393840 is about 19984.8402545529. The cubic root of 399393840 is about 736.4339261442.

The spelling of 399393840 in words is "three hundred ninety-nine million, three hundred ninety-three thousand, eight hundred forty".