399165900 has 144 divisors (see below), whose sum is σ = 1340080896. Its totient is φ = 89844480.

The previous prime is 399165863. The next prime is 399165901. The reversal of 399165900 is 9561993.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (399165901) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 139282 + ... + 142118.

Almost surely, 2^399165900 is an apocalyptic number.

399165900 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 399165900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (670040448).

399165900 is an abundant number, since it is smaller than the sum of its proper divisors (940914996).

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

399165900 is a wasteful number, since it uses less digits than its factorization.

399165900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2928 (or 2921 counting only the distinct ones).

The product of its (nonzero) digits is 65610, while the sum is 42.

The square root of 399165900 is about 19979.1366179823. The cubic root of 399165900 is about 736.2938015551.

It can be divided in two parts, 399165 and 900, that added together give a triangular number (400065 = T₈₉₄).

The spelling of 399165900 in words is "three hundred ninety-nine million, one hundred sixty-five thousand, nine hundred".