644258530944 has 640 divisors, whose sum is σ = 2234316691200. Its totient is φ = 180484816896.

The previous prime is 644258530913. The next prime is 644258530963. The reversal of 644258530944 is 449035852446.

644258530944 is a `hidden beast` number, since 6 + 44 + 25 + 8 + 530 + 9 + 44 = 666.

It is a super-3 number, since 3×644258530944³ (a number of 36 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

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

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 1467559077 + ... + 1467559515.

It is an arithmetic number, because the mean of its divisors is an integer number (3491119830).

Almost surely, 2^644258530944 is an apocalyptic number.

644258530944 is a gapful number since it is divisible by the number (64) 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 644258530944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1117158345600).

644258530944 is an abundant number, since it is smaller than the sum of its proper divisors (1590058160256).

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

644258530944 is a wasteful number, since it uses less digits than its factorization.

644258530944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 822 (or 801 counting only the distinct ones).

The product of its (nonzero) digits is 16588800, while the sum is 54.

The spelling of 644258530944 in words is "six hundred forty-four billion, two hundred fifty-eight million, five hundred thirty thousand, nine hundred forty-four".