399409920 has 576 divisors, whose sum is σ = 1758167040. Its totient is φ = 83607552.

The previous prime is 399409919. The next prime is 399410009. The reversal of 399409920 is 29904993.

It is a tau number, because it is divible by the number of its divisors (576).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3144897 + ... + 3145023.

Almost surely, 2^399409920 is an apocalyptic number.

399409920 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 399409920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (879083520).

399409920 is an abundant number, since it is smaller than the sum of its proper divisors (1358757120).

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

399409920 is a wasteful number, since it uses less digits than its factorization.

399409920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 177 (or 157 counting only the distinct ones).

The product of its (nonzero) digits is 157464, while the sum is 45.

The square root of 399409920 is about 19985.2425554458. The cubic root of 399409920 is about 736.4438092031.

The spelling of 399409920 in words is "three hundred ninety-nine million, four hundred nine thousand, nine hundred twenty".