6638417856 has 504 divisors, whose sum is σ = 24069625216. Its totient is φ = 1776660480.

The previous prime is 6638417801. The next prime is 6638417857. The reversal of 6638417856 is 6587148366.

It is a tau number, because it is divible by the number of its divisors (504).

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

Its product of digits (5806080) is a multiple of the sum of its prime divisors (240).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6638417857) by changing a digit.

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 71 ways as a sum of consecutive naturals, for example, 31461591 + ... + 31461801.

Almost surely, 2^6638417856 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 6638417856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12034812608).

6638417856 is an abundant number, since it is smaller than the sum of its proper divisors (17431207360).

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

6638417856 is a wasteful number, since it uses less digits than its factorization.

6638417856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 279 (or 240 counting only the distinct ones).

The product of its digits is 5806080, while the sum is 54.

The square root of 6638417856 is about 81476.4865221863. The cubic root of 6638417856 is about 1879.4099793255.

The spelling of 6638417856 in words is "six billion, six hundred thirty-eight million, four hundred seventeen thousand, eight hundred fifty-six".