644649164 has 12 divisors (see below), whose sum is σ = 1142416800. Its totient is φ = 318244368.

The previous prime is 644649151. The next prime is 644649167. The reversal of 644649164 is 461946446.

It is not an unprimeable number, because it can be changed into a prime (644649167) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1019699 + ... + 1020330.

It is an arithmetic number, because the mean of its divisors is an integer number (95201400).

Almost surely, 2^644649164 is an apocalyptic number.

It is an amenable number.

644649164 is a deficient number, since it is larger than the sum of its proper divisors (497767636).

644649164 is a wasteful number, since it uses less digits than its factorization.

644649164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2040112 (or 2040110 counting only the distinct ones).

The product of its digits is 497664, while the sum is 44.

The square root of 644649164 is about 25389.9421818956. The cubic root of 644649164 is about 863.8555767831.

The spelling of 644649164 in words is "six hundred forty-four million, six hundred forty-nine thousand, one hundred sixty-four".