399924 has 72 divisors (see below), whose sum is σ = 1238720. Its totient is φ = 109296.

The previous prime is 399913. The next prime is 399937. The reversal of 399924 is 429993.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a zygodrome in base 13.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17377 + ... + 17399.

2³⁹⁹⁹²⁴ 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 399924, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (619360).

399924 is an abundant number, since it is smaller than the sum of its proper divisors (838796).

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

399924 is a wasteful number, since it uses less digits than its factorization.

399924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66 (or 35 counting only the distinct ones).

The product of its digits is 17496, while the sum is 36.

The square root of 399924 is about 632.3954459039. The cubic root of 399924 is about 73.6759632373.

The spelling of 399924 in words is "three hundred ninety-nine thousand, nine hundred twenty-four".