644608 has 20 divisors (see below), whose sum is σ = 1288980. Its totient is φ = 322048.

The previous prime is 644599. The next prime is 644617. The reversal of 644608 is 806446.

It is an interprime number because it is at equal distance from previous prime (644599) and next prime (644617).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 118 + ... + 1141.

It is an arithmetic number, because the mean of its divisors is an integer number (64449).

2⁶⁴⁴⁶⁰⁸ is an apocalyptic number.

It is an amenable number.

644608 is a deficient number, since it is larger than the sum of its proper divisors (644372).

644608 is an equidigital number, since it uses as much as digits as its factorization.

644608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1277 (or 1261 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 644608 is about 802.8748345788. The cubic root of 644608 is about 86.3837189258.

Subtracting from 644608 its product of nonzero digits (4608), we obtain a square (640000 = 800²).

The spelling of 644608 in words is "six hundred forty-four thousand, six hundred eight".