6440644044 has 36 divisors (see below), whose sum is σ = 16883501544. Its totient is φ = 2146881024.

The previous prime is 6440644031. The next prime is 6440644079. The reversal of 6440644044 is 4404460446.

6440644044 is a `hidden beast` number, since 6 + 4 + 4 + 0 + 644 + 0 + 4 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3312117 + ... + 3314060.

It is an arithmetic number, because the mean of its divisors is an integer number (468986154).

Almost surely, 2^6440644044 is an apocalyptic number.

It is an amenable number.

6440644044 is an abundant number, since it is smaller than the sum of its proper divisors (10442857500).

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

6440644044 is a wasteful number, since it uses less digits than its factorization.

6440644044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6626196 (or 6626182 counting only the distinct ones).

The product of its (nonzero) digits is 147456, while the sum is 36.

The square root of 6440644044 is about 80253.6232453090. The cubic root of 6440644044 is about 1860.5575123763.

The spelling of 6440644044 in words is "six billion, four hundred forty million, six hundred forty-four thousand, forty-four".