6440644568 has 32 divisors (see below), whose sum is σ = 12895632000. Its totient is φ = 3008974080.

The previous prime is 6440644559. The next prime is 6440644579. The reversal of 6440644568 is 8654460446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 440573 + ... + 454956.

It is an arithmetic number, because the mean of its divisors is an integer number (402988500).

Almost surely, 2^6440644568 is an apocalyptic number.

It is an amenable number.

6440644568 is an abundant number, since it is smaller than the sum of its proper divisors (6454987432).

6440644568 is a wasteful number, since it uses less digits than its factorization.

6440644568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 895595 (or 895591 counting only the distinct ones).

The product of its (nonzero) digits is 2211840, while the sum is 47.

The square root of 6440644568 is about 80253.6265099590. The cubic root of 6440644568 is about 1860.5575628335.

The spelling of 6440644568 in words is "six billion, four hundred forty million, six hundred forty-four thousand, five hundred sixty-eight".