644922 has 24 divisors (see below), whose sum is σ = 1450176. Its totient is φ = 214812.

The previous prime is 644911. The next prime is 644923. The reversal of 644922 is 229446.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644922.

It is not an unprimeable number, because it can be changed into a prime (644923) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 178 + ... + 1149.

It is an arithmetic number, because the mean of its divisors is an integer number (60424).

2⁶⁴⁴⁹²² is an apocalyptic number.

644922 is an abundant number, since it is smaller than the sum of its proper divisors (805254).

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

644922 is a wasteful number, since it uses less digits than its factorization.

644922 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1344 (or 1332 counting only the distinct ones).

The product of its digits is 3456, while the sum is 27.

The square root of 644922 is about 803.0703580634. The cubic root of 644922 is about 86.3977429966.

The spelling of 644922 in words is "six hundred forty-four thousand, nine hundred twenty-two".