644646646446 has 64 divisors (see below), whose sum is σ = 1428335030016. Its totient is φ = 192318508800.

The previous prime is 644646646433. The next prime is 644646646459.

644646646446 is nontrivially palindromic in base 10.

It is an interprime number because it is at equal distance from previous prime (644646646433) and next prime (644646646459).

It is a self number, because there is not a number n which added to its sum of digits gives 644646646446.

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 31 ways as a sum of consecutive naturals, for example, 7621266 + ... + 7705386.

It is an arithmetic number, because the mean of its divisors is an integer number (22317734844).

Almost surely, 2^644646646446 is an apocalyptic number.

644646646446 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 644646646446, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (714167515008).

644646646446 is an abundant number, since it is smaller than the sum of its proper divisors (783688383570).

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

644646646446 is a wasteful number, since it uses less digits than its factorization.

644646646446 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85937.

The product of its digits is 191102976, while the sum is 60.

The spelling of 644646646446 in words is "six hundred forty-four billion, six hundred forty-six million, six hundred forty-six thousand, four hundred forty-six".