644506656222 has 128 divisors (see below), whose sum is σ = 1566669081600. Its totient is φ = 174142080000.

The previous prime is 644506656169. The next prime is 644506656239. The reversal of 644506656222 is 222656605446.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3462279 + ... + 3643677.

It is an arithmetic number, because the mean of its divisors is an integer number (12239602200).

Almost surely, 2^644506656222 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644506656222, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (783334540800).

644506656222 is an abundant number, since it is smaller than the sum of its proper divisors (922162425378).

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

644506656222 is a wasteful number, since it uses less digits than its factorization.

644506656222 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181570.

The product of its (nonzero) digits is 4147200, while the sum is 48.

The spelling of 644506656222 in words is "six hundred forty-four billion, five hundred six million, six hundred fifty-six thousand, two hundred twenty-two".