644022006 has 16 divisors (see below), whose sum is σ = 1288714224. Its totient is φ = 214562304.

The previous prime is 644021981. The next prime is 644022061. The reversal of 644022006 is 600220446.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14971 + ... + 38886.

It is an arithmetic number, because the mean of its divisors is an integer number (80544639).

Almost surely, 2^644022006 is an apocalyptic number.

644022006 is an abundant number, since it is smaller than the sum of its proper divisors (644692218).

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

644022006 is a wasteful number, since it uses less digits than its factorization.

644022006 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55855.

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

The square root of 644022006 is about 25377.5886561352. The cubic root of 644022006 is about 863.5753469814.

The spelling of 644022006 in words is "six hundred forty-four million, twenty-two thousand, six".