644122164 has 48 divisors (see below), whose sum is σ = 1738372608. Its totient is φ = 181815648.

The previous prime is 644122133. The next prime is 644122189. The reversal of 644122164 is 461221446.

It is a happy number.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39222 + ... + 53165.

It is an arithmetic number, because the mean of its divisors is an integer number (36216096).

Almost surely, 2^644122164 is an apocalyptic number.

It is an amenable number.

644122164 is an abundant number, since it is smaller than the sum of its proper divisors (1094250444).

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

644122164 is a wasteful number, since it uses less digits than its factorization.

644122164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92484 (or 92482 counting only the distinct ones).

The product of its digits is 9216, while the sum is 30.

The square root of 644122164 is about 25379.5619347537. The cubic root of 644122164 is about 863.6201122717.

The spelling of 644122164 in words is "six hundred forty-four million, one hundred twenty-two thousand, one hundred sixty-four".