644805960960 has 288 divisors, whose sum is σ = 2477414338560. Its totient is φ = 139627044864.

The previous prime is 644805960923. The next prime is 644805960977. The reversal of 644805960960 is 69069508446.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a self number, because there is not a number n which added to its sum of digits gives 644805960960.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 120552 + ... + 1141991.

It is an arithmetic number, because the mean of its divisors is an integer number (8602133120).

Almost surely, 2^644805960960 is an apocalyptic number.

644805960960 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 644805960960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1238707169280).

644805960960 is an abundant number, since it is smaller than the sum of its proper divisors (1832608377600).

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

644805960960 is a wasteful number, since it uses less digits than its factorization.

644805960960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1262593 (or 1262579 counting only the distinct ones).

The product of its (nonzero) digits is 11197440, while the sum is 57.

The spelling of 644805960960 in words is "six hundred forty-four billion, eight hundred five million, nine hundred sixty thousand, nine hundred sixty".