644438311887 has 8 divisors (see below), whose sum is σ = 880208426160. Its totient is φ = 419146869440.

The previous prime is 644438311877. The next prime is 644438311963. The reversal of 644438311887 is 788113834446.

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 644438311887 - 2⁶ = 644438311823 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644438311807) 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, 2619667812 + ... + 2619668057.

It is an arithmetic number, because the mean of its divisors is an integer number (110026053270).

Almost surely, 2^644438311887 is an apocalyptic number.

644438311887 is a deficient number, since it is larger than the sum of its proper divisors (235770114273).

644438311887 is a wasteful number, since it uses less digits than its factorization.

644438311887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5239335913.

The product of its digits is 12386304, while the sum is 57.

The spelling of 644438311887 in words is "six hundred forty-four billion, four hundred thirty-eight million, three hundred eleven thousand, eight hundred eighty-seven".