399440 has 20 divisors (see below), whose sum is σ = 928884. Its totient is φ = 159744.

The previous prime is 399439. The next prime is 399473. The reversal of 399440 is 44993.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 141376 + 258064 = 376^2 + 508^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2417 + ... + 2576.

2³⁹⁹⁴⁴⁰ is an apocalyptic number.

It is an amenable number.

399440 is an abundant number, since it is smaller than the sum of its proper divisors (529444).

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

399440 is a wasteful number, since it uses less digits than its factorization.

399440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5006 (or 5000 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 29.

The square root of 399440 is about 632.0126581011. The cubic root of 399440 is about 73.6462296203.

The spelling of 399440 in words is "three hundred ninety-nine thousand, four hundred forty".