644386206912 has 112 divisors (see below), whose sum is σ = 1951024995072. Its totient is φ = 183871872000.

The previous prime is 644386206911. The next prime is 644386206913. The reversal of 644386206912 is 219602683446.

It is an interprime number because it is at equal distance from previous prime (644386206911) and next prime (644386206913).

It is a tau number, because it is divible by the number of its divisors (112).

It is not an unprimeable number, because it can be changed into a prime (644386206911) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 728787 + ... + 1349037.

Almost surely, 2^644386206912 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 644386206912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (975512497536).

644386206912 is an abundant number, since it is smaller than the sum of its proper divisors (1306638788160).

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

644386206912 is a wasteful number, since it uses less digits than its factorization.

644386206912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 621046 (or 621036 counting only the distinct ones).

The product of its (nonzero) digits is 2985984, while the sum is 51.

The spelling of 644386206912 in words is "six hundred forty-four billion, three hundred eighty-six million, two hundred six thousand, nine hundred twelve".