6638906664 has 128 divisors (see below), whose sum is σ = 20545056000. Its totient is φ = 1972276992.

The previous prime is 6638906609. The next prime is 6638906683. The reversal of 6638906664 is 4666098366.

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

It is a self number, because there is not a number n which added to its sum of digits gives 6638906664.

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 31 ways as a sum of consecutive naturals, for example, 40669 + ... + 122195.

It is an arithmetic number, because the mean of its divisors is an integer number (160508250).

Almost surely, 2^6638906664 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 6638906664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10272528000).

6638906664 is an abundant number, since it is smaller than the sum of its proper divisors (13906149336).

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

6638906664 is a wasteful number, since it uses less digits than its factorization.

6638906664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81584 (or 81574 counting only the distinct ones).

The product of its (nonzero) digits is 6718464, while the sum is 54.

The square root of 6638906664 is about 81479.4861544917. The cubic root of 6638906664 is about 1879.4561071884.

The spelling of 6638906664 in words is "six billion, six hundred thirty-eight million, nine hundred six thousand, six hundred sixty-four".