644567 has 12 divisors (see below), whose sum is σ = 810768. Its totient is φ = 501600.

The previous prime is 644563. The next prime is 644569. The reversal of 644567 is 765446.

It is not a de Polignac number, because 644567 - 2² = 644563 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644563) 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 11 ways as a sum of consecutive naturals, for example, 467 + ... + 1227.

It is an arithmetic number, because the mean of its divisors is an integer number (67564).

2⁶⁴⁴⁵⁶⁷ is an apocalyptic number.

644567 is a deficient number, since it is larger than the sum of its proper divisors (166201).

644567 is a wasteful number, since it uses less digits than its factorization.

644567 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 790 (or 779 counting only the distinct ones).

The product of its digits is 20160, while the sum is 32.

The square root of 644567 is about 802.8493009276. The cubic root of 644567 is about 86.3818874212.

The spelling of 644567 in words is "six hundred forty-four thousand, five hundred sixty-seven".