644264223632 has 80 divisors (see below), whose sum is σ = 1335547519488. Its totient is φ = 300330792960.

The previous prime is 644264223611. The next prime is 644264223637. The reversal of 644264223632 is 236322462446.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (644264223637) 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, 16622708 + ... + 16661420.

Almost surely, 2^644264223632 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 644264223632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (667773759744).

644264223632 is an abundant number, since it is smaller than the sum of its proper divisors (691283295856).

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

644264223632 is a wasteful number, since it uses less digits than its factorization.

644264223632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39888 (or 39882 counting only the distinct ones).

The product of its digits is 1990656, while the sum is 44.

The spelling of 644264223632 in words is "six hundred forty-four billion, two hundred sixty-four million, two hundred twenty-three thousand, six hundred thirty-two".