644507031168 has 1920 divisors, whose sum is σ = 2751499808640. Its totient is φ = 144919756800.

The previous prime is 644507031163. The next prime is 644507031227. The reversal of 644507031168 is 861130705446.

644507031168 is a `hidden beast` number, since 6 + 4 + 450 + 7 + 0 + 31 + 168 = 666.

It is not an unprimeable number, because it can be changed into a prime (644507031163) by changing a digit.

It is a polite number, since it can be written in 239 ways as a sum of consecutive naturals, for example, 2293619188 + ... + 2293619468.

It is an arithmetic number, because the mean of its divisors is an integer number (1433072817).

Almost surely, 2^644507031168 is an apocalyptic number.

644507031168 is a gapful number since it is divisible by the number (68) 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 644507031168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1375749904320).

644507031168 is an abundant number, since it is smaller than the sum of its proper divisors (2106992777472).

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

644507031168 is a wasteful number, since it uses less digits than its factorization.

644507031168 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 368 (or 334 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 45.

The spelling of 644507031168 in words is "six hundred forty-four billion, five hundred seven million, thirty-one thousand, one hundred sixty-eight".