644976679446 has 96 divisors (see below), whose sum is σ = 1540794292128. Its totient is φ = 193358776320.

The previous prime is 644976679421. The next prime is 644976679469.

644976679446 is a `hidden beast` number, since 6 + 4 + 49 + 76 + 6 + 79 + 446 = 666.

644976679446 is nontrivially palindromic in base 10.

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 47 ways as a sum of consecutive naturals, for example, 70615896 + ... + 70625028.

It is an arithmetic number, because the mean of its divisors is an integer number (16049940543).

Almost surely, 2^644976679446 is an apocalyptic number.

644976679446 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 644976679446, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (770397146064).

644976679446 is an abundant number, since it is smaller than the sum of its proper divisors (895817612682).

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

644976679446 is a wasteful number, since it uses less digits than its factorization.

644976679446 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12926 (or 12923 counting only the distinct ones).

The product of its digits is 1316818944, while the sum is 72.

The spelling of 644976679446 in words is "six hundred forty-four billion, nine hundred seventy-six million, six hundred seventy-nine thousand, four hundred forty-six".