644266689 has 16 divisors (see below), whose sum is σ = 952480704. Its totient is φ = 384062400.

The previous prime is 644266643. The next prime is 644266699. The reversal of 644266689 is 986662446.

644266689 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644266689 - 2²⁷ = 510048961 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644266619) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 158014 + ... + 162039.

It is an arithmetic number, because the mean of its divisors is an integer number (59530044).

Almost surely, 2^644266689 is an apocalyptic number.

It is an amenable number.

644266689 is a deficient number, since it is larger than the sum of its proper divisors (308214015).

644266689 is a wasteful number, since it uses less digits than its factorization.

644266689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320128.

The product of its digits is 2985984, while the sum is 51.

The square root of 644266689 is about 25382.4090464243. The cubic root of 644266689 is about 863.6846990689.

The spelling of 644266689 in words is "six hundred forty-four million, two hundred sixty-six thousand, six hundred eighty-nine".