644688886446 has 144 divisors (see below), whose sum is σ = 1610409632832. Its totient is φ = 186034907520.

The previous prime is 644688886427. The next prime is 644688886447.

It is a happy number.

644688886446 is a `hidden beast` number, since 6 + 4 + 468 + 88 + 86 + 4 + 4 + 6 = 666.

644688886446 is nontrivially palindromic in base 10.

It is a super-3 number, since 3×644688886446³ (a number of 36 digits) contains 333 as substring.

644688886446 is a modest number, since divided by 886446 gives 644688 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644688886447) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 3702436 + ... + 3872648.

It is an arithmetic number, because the mean of its divisors is an integer number (11183400228).

Almost surely, 2^644688886446 is an apocalyptic number.

644688886446 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 644688886446, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (805204816416).

644688886446 is an abundant number, since it is smaller than the sum of its proper divisors (965720746386).

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

644688886446 is a wasteful number, since it uses less digits than its factorization.

644688886446 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170327 (or 170313 counting only the distinct ones).

The product of its digits is 1358954496, while the sum is 72.

The spelling of 644688886446 in words is "six hundred forty-four billion, six hundred eighty-eight million, eight hundred eighty-six thousand, four hundred forty-six".