644137016679 has 24 divisors (see below), whose sum is σ = 1006183389120. Its totient is φ = 394733449152.

The previous prime is 644137016659. The next prime is 644137016711. The reversal of 644137016679 is 976610731446.

644137016679 is a `hidden beast` number, since 6 + 4 + 41 + 370 + 166 + 79 = 666.

It is not a de Polignac number, because 644137016679 - 2²⁷ = 644002798951 is a prime.

It is a super-2 number, since 2×644137016679² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644137016659) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11489704 + ... + 11545629.

It is an arithmetic number, because the mean of its divisors is an integer number (41924307880).

Almost surely, 2^644137016679 is an apocalyptic number.

644137016679 is a deficient number, since it is larger than the sum of its proper divisors (362046372441).

644137016679 is a wasteful number, since it uses less digits than its factorization.

644137016679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23035591 (or 23035588 counting only the distinct ones).

The product of its (nonzero) digits is 4572288, while the sum is 54.

The spelling of 644137016679 in words is "six hundred forty-four billion, one hundred thirty-seven million, sixteen thousand, six hundred seventy-nine".