644590423209 has 4 divisors (see below), whose sum is σ = 859453897616. Its totient is φ = 429726948804.

The previous prime is 644590423201. The next prime is 644590423261. The reversal of 644590423209 is 902324095446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 644590423209 - 2³ = 644590423201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644590423201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107431737199 + ... + 107431737204.

It is an arithmetic number, because the mean of its divisors is an integer number (214863474404).

Almost surely, 2^644590423209 is an apocalyptic number.

It is an amenable number.

644590423209 is a deficient number, since it is larger than the sum of its proper divisors (214863474407).

644590423209 is a wasteful number, since it uses less digits than its factorization.

644590423209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214863474406.

The product of its (nonzero) digits is 1866240, while the sum is 48.

The spelling of 644590423209 in words is "six hundred forty-four billion, five hundred ninety million, four hundred twenty-three thousand, two hundred nine".