644622 has 16 divisors (see below), whose sum is σ = 1406592. Its totient is φ = 195320.

The previous prime is 644617. The next prime is 644629. The reversal of 644622 is 226446.

644622 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 644592 and 644601.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644622.

It is not an unprimeable number, because it can be changed into a prime (644629) by changing a digit.

644622 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4818 + ... + 4949.

It is an arithmetic number, because the mean of its divisors is an integer number (87912).

2⁶⁴⁴⁶²² is an apocalyptic number.

644622 is an abundant number, since it is smaller than the sum of its proper divisors (761970).

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

644622 is a wasteful number, since it uses less digits than its factorization.

644622 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9783.

The product of its digits is 2304, while the sum is 24.

The square root of 644622 is about 802.8835532006. The cubic root of 644622 is about 86.3843442998.

The spelling of 644622 in words is "six hundred forty-four thousand, six hundred twenty-two".