6399978 has 16 divisors (see below), whose sum is σ = 13784736. Its totient is φ = 1969200.

The previous prime is 6399971. The next prime is 6400013. The reversal of 6399978 is 8799936.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 6399978.

It is not an unprimeable number, because it can be changed into a prime (6399971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40948 + ... + 41103.

It is an arithmetic number, because the mean of its divisors is an integer number (861546).

Almost surely, 2^6399978 is an apocalyptic number.

6399978 is an abundant number, since it is smaller than the sum of its proper divisors (7384758).

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

6399978 is a wasteful number, since it uses less digits than its factorization.

6399978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82069.

The product of its digits is 734832, while the sum is 51.

The square root of 6399978 is about 2529.8177799992. The cubic root of 6399978 is about 185.6633406048.

The spelling of 6399978 in words is "six million, three hundred ninety-nine thousand, nine hundred seventy-eight".