6399856872864 has 3072 divisors, whose sum is σ = 27027302400000. Its totient is φ = 1453768114176.

The previous prime is 6399856872859. The next prime is 6399856872887. The reversal of 6399856872864 is 4682786589936.

It is a happy number.

6399856872864 is a `hidden beast` number, since 6 + 399 + 85 + 6 + 8 + 72 + 86 + 4 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 511 ways as a sum of consecutive naturals, for example, 46042135707 + ... + 46042135845.

It is an arithmetic number, because the mean of its divisors is an integer number (8797950000).

Almost surely, 2^{6399856872864} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6399856872864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13513651200000).

6399856872864 is an abundant number, since it is smaller than the sum of its proper divisors (20627445527136).

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

6399856872864 is a wasteful number, since it uses less digits than its factorization.

6399856872864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265 (or 237 counting only the distinct ones).

The product of its digits is 7524679680, while the sum is 81.

The spelling of 6399856872864 in words is "six trillion, three hundred ninety-nine billion, eight hundred fifty-six million, eight hundred seventy-two thousand, eight hundred sixty-four".