644926244 has 12 divisors (see below), whose sum is σ = 1167539100. Its totient is φ = 311343648.

The previous prime is 644926241. The next prime is 644926283. The reversal of 644926244 is 442629446.

It can be written as a sum of positive squares in 2 ways, for example, as 200222500 + 444703744 = 14150^2 + 21088^2 .

It is not an unprimeable number, because it can be changed into a prime (644926241) 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, 2779739 + ... + 2779970.

It is an arithmetic number, because the mean of its divisors is an integer number (97294925).

Almost surely, 2^644926244 is an apocalyptic number.

It is an amenable number.

644926244 is a deficient number, since it is larger than the sum of its proper divisors (522612856).

644926244 is a wasteful number, since it uses less digits than its factorization.

644926244 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5559742 (or 5559740 counting only the distinct ones).

The product of its digits is 331776, while the sum is 41.

The square root of 644926244 is about 25395.3980870551. The cubic root of 644926244 is about 863.9793251368.

The spelling of 644926244 in words is "six hundred forty-four million, nine hundred twenty-six thousand, two hundred forty-four".