644928 has 28 divisors (see below), whose sum is σ = 1706880. Its totient is φ = 214912.

The previous prime is 644923. The next prime is 644933. The reversal of 644928 is 829446.

It is an interprime number because it is at equal distance from previous prime (644923) and next prime (644933).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644923) by changing a digit.

644928 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1488 + ... + 1871.

It is an arithmetic number, because the mean of its divisors is an integer number (60960).

2⁶⁴⁴⁹²⁸ is an apocalyptic number.

It is an amenable number.

644928 is an abundant number, since it is smaller than the sum of its proper divisors (1061952).

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

644928 is a wasteful number, since it uses less digits than its factorization.

644928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3374 (or 3364 counting only the distinct ones).

The product of its digits is 13824, while the sum is 33.

The square root of 644928 is about 803.0740937174. The cubic root of 644928 is about 86.3980109281.

The spelling of 644928 in words is "six hundred forty-four thousand, nine hundred twenty-eight".