399864 has 16 divisors (see below), whose sum is σ = 999720. Its totient is φ = 133280.

The previous prime is 399853. The next prime is 399871. The reversal of 399864 is 468993.

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

399864 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8307 + ... + 8354.

2³⁹⁹⁸⁶⁴ is an apocalyptic number.

It is an amenable number.

399864 is an abundant number, since it is smaller than the sum of its proper divisors (599856).

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

399864 is a wasteful number, since it uses less digits than its factorization.

399864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16670 (or 16666 counting only the distinct ones).

The product of its digits is 46656, while the sum is 39.

The square root of 399864 is about 632.3480054527. The cubic root of 399864 is about 73.6722785548.

The spelling of 399864 in words is "three hundred ninety-nine thousand, eight hundred sixty-four".