644023005 has 8 divisors (see below), whose sum is σ = 1030436832. Its totient is φ = 343478928.

The previous prime is 644022989. The next prime is 644023007. The reversal of 644023005 is 500320446.

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

It is not a de Polignac number, because 644023005 - 2⁴ = 644022989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644023007) 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, 21467419 + ... + 21467448.

It is an arithmetic number, because the mean of its divisors is an integer number (128804604).

Almost surely, 2^644023005 is an apocalyptic number.

It is an amenable number.

644023005 is a deficient number, since it is larger than the sum of its proper divisors (386413827).

644023005 is a wasteful number, since it uses less digits than its factorization.

644023005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42934875.

The product of its (nonzero) digits is 2880, while the sum is 24.

The square root of 644023005 is about 25377.6083388486. The cubic root of 644023005 is about 863.5757935041.

The spelling of 644023005 in words is "six hundred forty-four million, twenty-three thousand, five".