644063958 has 48 divisors (see below), whose sum is σ = 1482652080. Its totient is φ = 201676608.

The previous prime is 644063951. The next prime is 644064007. The reversal of 644063958 is 859360446.

644063958 is a `hidden beast` number, since 6 + 4 + 4 + 0 + 639 + 5 + 8 = 666.

644063958 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644063951) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2641 + ... + 35987.

It is an arithmetic number, because the mean of its divisors is an integer number (30888585).

Almost surely, 2^644063958 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644063958, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (741326040).

644063958 is an abundant number, since it is smaller than the sum of its proper divisors (838588122).

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

644063958 is a wasteful number, since it uses less digits than its factorization.

644063958 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33421 (or 33418 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 45.

The square root of 644063958 is about 25378.4151987471. The cubic root of 644063958 is about 863.5940978554.

The spelling of 644063958 in words is "six hundred forty-four million, sixty-three thousand, nine hundred fifty-eight".