644130101538 has 192 divisors, whose sum is σ = 1751268729600. Its totient is φ = 166224199680.

The previous prime is 644130101477. The next prime is 644130101597. The reversal of 644130101538 is 835101031446.

644130101538 is a `hidden beast` number, since 6 + 4 + 4 + 13 + 0 + 101 + 538 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 376903828 + ... + 376905536.

It is an arithmetic number, because the mean of its divisors is an integer number (9121191300).

Almost surely, 2^644130101538 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644130101538, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (875634364800).

644130101538 is an abundant number, since it is smaller than the sum of its proper divisors (1107138628062).

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

644130101538 is a wasteful number, since it uses less digits than its factorization.

644130101538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3337 (or 3334 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The spelling of 644130101538 in words is "six hundred forty-four billion, one hundred thirty million, one hundred one thousand, five hundred thirty-eight".