644420328 has 16 divisors (see below), whose sum is σ = 1611050880. Its totient is φ = 214806768.

The previous prime is 644420327. The next prime is 644420347. The reversal of 644420328 is 823024446.

It is not an unprimeable number, because it can be changed into a prime (644420327) 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, 13425400 + ... + 13425447.

It is an arithmetic number, because the mean of its divisors is an integer number (100690680).

Almost surely, 2^644420328 is an apocalyptic number.

It is an amenable number.

644420328 is an abundant number, since it is smaller than the sum of its proper divisors (966630552).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644420328 is a wasteful number, since it uses less digits than its factorization.

644420328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26850856 (or 26850852 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 33.

The square root of 644420328 is about 25385.4353517918. The cubic root of 644420328 is about 863.7533482319.

The spelling of 644420328 in words is "six hundred forty-four million, four hundred twenty thousand, three hundred twenty-eight".