644241968 has 40 divisors (see below), whose sum is σ = 1317051120. Its totient is φ = 304439040.

The previous prime is 644241967. The next prime is 644241973. The reversal of 644241968 is 869142446.

It is not an unprimeable number, because it can be changed into a prime (644241967) 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 7 ways as a sum of consecutive naturals, for example, 137846 + ... + 142442.

It is an arithmetic number, because the mean of its divisors is an integer number (32926278).

Almost surely, 2^644241968 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 644241968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (658525560).

644241968 is an abundant number, since it is smaller than the sum of its proper divisors (672809152).

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

644241968 is a wasteful number, since it uses less digits than its factorization.

644241968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5085 (or 5079 counting only the distinct ones).

The product of its digits is 331776, while the sum is 44.

The square root of 644241968 is about 25381.9220706392. The cubic root of 644241968 is about 863.6736521827.

The spelling of 644241968 in words is "six hundred forty-four million, two hundred forty-one thousand, nine hundred sixty-eight".