644230928 has 20 divisors (see below), whose sum is σ = 1361670288. Its totient is φ = 292832160.

The previous prime is 644230921. The next prime is 644230957. The reversal of 644230928 is 829032446.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 644230891 and 644230900.

It is not an unprimeable number, because it can be changed into a prime (644230921) 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, 1830026 + ... + 1830377.

Almost surely, 2^644230928 is an apocalyptic number.

It is an amenable number.

644230928 is an abundant number, since it is smaller than the sum of its proper divisors (717439360).

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

644230928 is a wasteful number, since it uses less digits than its factorization.

644230928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3660422 (or 3660416 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 38.

The square root of 644230928 is about 25381.7045920876. The cubic root of 644230928 is about 863.6687187301.

The spelling of 644230928 in words is "six hundred forty-four million, two hundred thirty thousand, nine hundred twenty-eight".