644258016 has 96 divisors (see below), whose sum is σ = 1896602400. Its totient is φ = 212751360.

The previous prime is 644258011. The next prime is 644258033. The reversal of 644258016 is 610852446.

644258016 is a `hidden beast` number, since 64 + 4 + 2 + 580 + 16 = 666.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644258011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 90756 + ... + 97596.

It is an arithmetic number, because the mean of its divisors is an integer number (19756275).

Almost surely, 2^644258016 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644258016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (948301200).

644258016 is an abundant number, since it is smaller than the sum of its proper divisors (1252344384).

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

644258016 is a wasteful number, since it uses less digits than its factorization.

644258016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6969 (or 6955 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The square root of 644258016 is about 25382.2381991817. The cubic root of 644258016 is about 863.6808234632.

The spelling of 644258016 in words is "six hundred forty-four million, two hundred fifty-eight thousand, sixteen".