644023138488 has 64 divisors (see below), whose sum is σ = 1616101818240. Its totient is φ = 213868854144.

The previous prime is 644023138457. The next prime is 644023138489. The reversal of 644023138488 is 884831320446.

644023138488 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×644023138488² (a number of 24 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 644023138488.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644023138489) 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, 45723495 + ... + 45737577.

It is an arithmetic number, because the mean of its divisors is an integer number (25251590910).

Almost surely, 2^644023138488 is an apocalyptic number.

It is an amenable number.

644023138488 is an abundant number, since it is smaller than the sum of its proper divisors (972078679752).

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

644023138488 is a wasteful number, since it uses less digits than its factorization.

644023138488 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21108 (or 21104 counting only the distinct ones).

The product of its (nonzero) digits is 3538944, while the sum is 51.

The spelling of 644023138488 in words is "six hundred forty-four billion, twenty-three million, one hundred thirty-eight thousand, four hundred eighty-eight".