644822 has 16 divisors (see below), whose sum is σ = 1036800. Its totient is φ = 299880.

The previous prime is 644801. The next prime is 644837. The reversal of 644822 is 228446.

It is a junction number, because it is equal to n+sod(n) for n = 644791 and 644800.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2579 + ... + 2817.

It is an arithmetic number, because the mean of its divisors is an integer number (64800).

2⁶⁴⁴⁸²² is an apocalyptic number.

644822 is a deficient number, since it is larger than the sum of its proper divisors (391978).

644822 is a wasteful number, since it uses less digits than its factorization.

644822 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331.

The product of its digits is 3072, while the sum is 26.

The square root of 644822 is about 803.0080946043. The cubic root of 644822 is about 86.3932772261.

The spelling of 644822 in words is "six hundred forty-four thousand, eight hundred twenty-two".