644663065 has 16 divisors (see below), whose sum is σ = 817747200. Its totient is φ = 486525312.

The previous prime is 644663057. The next prime is 644663081. The reversal of 644663065 is 560366446.

644663065 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 644663065 - 2³ = 644663057 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8509 + ... + 36901.

It is an arithmetic number, because the mean of its divisors is an integer number (51109200).

Almost surely, 2^644663065 is an apocalyptic number.

It is an amenable number.

644663065 is a deficient number, since it is larger than the sum of its proper divisors (173084135).

644663065 is a wasteful number, since it uses less digits than its factorization.

644663065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28656.

The product of its (nonzero) digits is 311040, while the sum is 40.

The square root of 644663065 is about 25390.2159305509. The cubic root of 644663065 is about 863.8617860365.

The spelling of 644663065 in words is "six hundred forty-four million, six hundred sixty-three thousand, sixty-five".