644872318141687 has 4 divisors (see below), whose sum is σ = 660600911267136. Its totient is φ = 629143725016240.

The previous prime is 644872318141679. The next prime is 644872318141699. The reversal of 644872318141687 is 786141813278446.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 644872318141687 - 2³ = 644872318141679 is a prime.

It is a super-3 number, since 3×644872318141687³ (a number of 45 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644872318141087) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7864296562663 + ... + 7864296562744.

It is an arithmetic number, because the mean of its divisors is an integer number (165150227816784).

Almost surely, 2^{644872318141687} is an apocalyptic number.

644872318141687 is a deficient number, since it is larger than the sum of its proper divisors (15728593125449).

644872318141687 is a wasteful number, since it uses less digits than its factorization.

644872318141687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15728593125448.

The product of its digits is 346816512, while the sum is 70.

The spelling of 644872318141687 in words is "six hundred forty-four trillion, eight hundred seventy-two billion, three hundred eighteen million, one hundred forty-one thousand, six hundred eighty-seven".