399656 has 8 divisors (see below), whose sum is σ = 749370. Its totient is φ = 199824.

The previous prime is 399647. The next prime is 399667. The reversal of 399656 is 656993.

It can be written as a sum of positive squares in only one way, i.e., 372100 + 27556 = 610^2 + 166^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

399656 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 24971 + ... + 24986.

2³⁹⁹⁶⁵⁶ is an apocalyptic number.

It is an amenable number.

399656 is a deficient number, since it is larger than the sum of its proper divisors (349714).

399656 is a wasteful number, since it uses less digits than its factorization.

399656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49963 (or 49959 counting only the distinct ones).

The product of its digits is 43740, while the sum is 38.

The square root of 399656 is about 632.1835176592. The cubic root of 399656 is about 73.6595021344.

The spelling of 399656 in words is "three hundred ninety-nine thousand, six hundred fifty-six".