644893947360 has 1152 divisors, whose sum is σ = 2615348736000. Its totient is φ = 143194521600.

The previous prime is 644893947349. The next prime is 644893947403. The reversal of 644893947360 is 63749398446.

644893947360 is a `hidden beast` number, since 6 + 4 + 489 + 3 + 94 + 7 + 3 + 60 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1292372391 + ... + 1292372889.

It is an arithmetic number, because the mean of its divisors is an integer number (2270268000).

Almost surely, 2^644893947360 is an apocalyptic number.

644893947360 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 644893947360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1307674368000).

644893947360 is an abundant number, since it is smaller than the sum of its proper divisors (1970454788640).

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

644893947360 is a wasteful number, since it uses less digits than its factorization.

644893947360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 712 (or 701 counting only the distinct ones).

The product of its (nonzero) digits is 94058496, while the sum is 63.

The spelling of 644893947360 in words is "six hundred forty-four billion, eight hundred ninety-three million, nine hundred forty-seven thousand, three hundred sixty".