644244442446 has 128 divisors (see below), whose sum is σ = 1534650416640. Its totient is φ = 178168896000.

The previous prime is 644244442441. The next prime is 644244442531.

It is a happy number.

644244442446 is nontrivially palindromic in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 644244442395 and 644244442404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644244442441) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4617460 + ... + 4754936.

It is an arithmetic number, because the mean of its divisors is an integer number (11989456380).

Almost surely, 2^644244442446 is an apocalyptic number.

644244442446 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 644244442446, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (767325208320).

644244442446 is an abundant number, since it is smaller than the sum of its proper divisors (890405974194).

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

644244442446 is a wasteful number, since it uses less digits than its factorization.

644244442446 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137650.

The product of its digits is 9437184, while the sum is 48.

The spelling of 644244442446 in words is "six hundred forty-four billion, two hundred forty-four million, four hundred forty-two thousand, four hundred forty-six".