644908 has 12 divisors (see below), whose sum is σ = 1231272. Its totient is φ = 293120.

The previous prime is 644899. The next prime is 644909. The reversal of 644908 is 809446.

It is a self number, because there is not a number n which added to its sum of digits gives 644908.

It is not an unprimeable number, because it can be changed into a prime (644909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7285 + ... + 7372.

It is an arithmetic number, because the mean of its divisors is an integer number (102606).

2⁶⁴⁴⁹⁰⁸ is an apocalyptic number.

It is an amenable number.

644908 is a deficient number, since it is larger than the sum of its proper divisors (586364).

644908 is a wasteful number, since it uses less digits than its factorization.

644908 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14672 (or 14670 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 644908 is about 803.0616414697. The cubic root of 644908 is about 86.3971178165.

The spelling of 644908 in words is "six hundred forty-four thousand, nine hundred eight".