644748 has 24 divisors (see below), whose sum is σ = 1620528. Its totient is φ = 198336.

The previous prime is 644747. The next prime is 644753. The reversal of 644748 is 847446.

644748 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644748.

It is not an unprimeable number, because it can be changed into a prime (644747) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1911 + ... + 2222.

It is an arithmetic number, because the mean of its divisors is an integer number (67522).

2⁶⁴⁴⁷⁴⁸ is an apocalyptic number.

It is an amenable number.

644748 is an abundant number, since it is smaller than the sum of its proper divisors (975780).

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

644748 is a wasteful number, since it uses less digits than its factorization.

644748 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4153 (or 4151 counting only the distinct ones).

The product of its digits is 21504, while the sum is 33.

The square root of 644748 is about 802.9620165363. The cubic root of 644748 is about 86.3899722587.

The spelling of 644748 in words is "six hundred forty-four thousand, seven hundred forty-eight".