399940 has 12 divisors (see below), whose sum is σ = 839916. Its totient is φ = 159968.

The previous prime is 399937. The next prime is 399941. The reversal of 399940 is 49993.

It can be written as a sum of positive squares in 2 ways, for example, as 254016 + 145924 = 504^2 + 382^2 .

It is a junction number, because it is equal to n+sod(n) for n = 399896 and 399905.

It is not an unprimeable number, because it can be changed into a prime (399941) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 9979 + ... + 10018.

It is an arithmetic number, because the mean of its divisors is an integer number (69993).

2³⁹⁹⁹⁴⁰ is an apocalyptic number.

It is an amenable number.

399940 is an abundant number, since it is smaller than the sum of its proper divisors (439976).

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

399940 is a wasteful number, since it uses less digits than its factorization.

399940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20006 (or 20004 counting only the distinct ones).

The product of its (nonzero) digits is 8748, while the sum is 34.

The square root of 399940 is about 632.4080960899. The cubic root of 399940 is about 73.6769457571.

The spelling of 399940 in words is "three hundred ninety-nine thousand, nine hundred forty".