644642530560 has 864 divisors, whose sum is σ = 2782738882560. Its totient is φ = 139582808064.

The previous prime is 644642530559. The next prime is 644642530573. The reversal of 644642530560 is 65035246446.

It is a happy number.

644642530560 is a `hidden beast` number, since 6 + 4 + 4 + 64 + 2 + 530 + 56 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (864).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 41360529 + ... + 41376111.

Almost surely, 2^644642530560 is an apocalyptic number.

644642530560 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644642530560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1391369441280).

644642530560 is an abundant number, since it is smaller than the sum of its proper divisors (2138096352000).

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

644642530560 is a wasteful number, since it uses less digits than its factorization.

644642530560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15645 (or 15619 counting only the distinct ones).

The product of its (nonzero) digits is 2073600, while the sum is 45.

The spelling of 644642530560 in words is "six hundred forty-four billion, six hundred forty-two million, five hundred thirty thousand, five hundred sixty".