644458464720 has 480 divisors, whose sum is σ = 2571035800320. Its totient is φ = 141544488960.

The previous prime is 644458464709. The next prime is 644458464721. The reversal of 644458464720 is 27464854446.

644458464720 is a `hidden beast` number, since 64 + 4 + 4 + 58 + 464 + 72 + 0 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644458464721) by changing a digit.

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 95 ways as a sum of consecutive naturals, for example, 30829312 + ... + 30850208.

It is an arithmetic number, because the mean of its divisors is an integer number (5356324584).

Almost surely, 2^644458464720 is an apocalyptic number.

644458464720 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 644458464720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1285517900160).

644458464720 is an abundant number, since it is smaller than the sum of its proper divisors (1926577335600).

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

644458464720 is a wasteful number, since it uses less digits than its factorization.

644458464720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21163 (or 21154 counting only the distinct ones).

The product of its (nonzero) digits is 20643840, while the sum is 54.

The spelling of 644458464720 in words is "six hundred forty-four billion, four hundred fifty-eight million, four hundred sixty-four thousand, seven hundred twenty".