644686262881 has 8 divisors (see below), whose sum is σ = 668508523200. Its totient is φ = 620970115920.

The previous prime is 644686262863. The next prime is 644686262911. The reversal of 644686262881 is 188262686446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644686262881 - 2³³ = 636096328289 is a prime.

It is a super-2 number, since 2×644686262881² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644686292881) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26515965 + ... + 26540266.

It is an arithmetic number, because the mean of its divisors is an integer number (83563565400).

Almost surely, 2^644686262881 is an apocalyptic number.

It is an amenable number.

644686262881 is a deficient number, since it is larger than the sum of its proper divisors (23822260319).

644686262881 is a wasteful number, since it uses less digits than its factorization.

644686262881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53056679.

The product of its digits is 42467328, while the sum is 61.

The spelling of 644686262881 in words is "six hundred forty-four billion, six hundred eighty-six million, two hundred sixty-two thousand, eight hundred eighty-one".