6399890 has 48 divisors (see below), whose sum is σ = 13801752. Its totient is φ = 2128896.

The previous prime is 6399889. The next prime is 6399917. The reversal of 6399890 is 989936.

It can be written as a sum of positive squares in 4 ways, for example, as 5900041 + 499849 = 2429^2 + 707^2 .

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17954 + ... + 18306.

Almost surely, 2^6399890 is an apocalyptic number.

6399890 is an abundant number, since it is smaller than the sum of its proper divisors (7401862).

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

6399890 is a wasteful number, since it uses less digits than its factorization.

6399890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 411 (or 404 counting only the distinct ones).

The product of its (nonzero) digits is 104976, while the sum is 44.

The square root of 6399890 is about 2529.8003873824. The cubic root of 6399890 is about 185.6624896410.

The spelling of 6399890 in words is "six million, three hundred ninety-nine thousand, eight hundred ninety".