644311065 has 16 divisors (see below), whose sum is σ = 1032627456. Its totient is φ = 343056000.

The previous prime is 644311051. The next prime is 644311069. The reversal of 644311065 is 560113446.

It is not a de Polignac number, because 644311065 - 2⁹ = 644310553 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (644311069) 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, 26721 + ... + 44750.

It is an arithmetic number, because the mean of its divisors is an integer number (64539216).

Almost surely, 2^644311065 is an apocalyptic number.

It is an amenable number.

644311065 is a deficient number, since it is larger than the sum of its proper divisors (388316391).

644311065 is a wasteful number, since it uses less digits than its factorization.

644311065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72080.

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 644311065 is about 25383.2831800774. The cubic root of 644311065 is about 863.7045283275.

The spelling of 644311065 in words is "six hundred forty-four million, three hundred eleven thousand, sixty-five".