664864555680 has 288 divisors, whose sum is σ = 2444300966016. Its totient is φ = 163597105152.

The previous prime is 664864555679. The next prime is 664864555829. The reversal of 664864555680 is 86555468466.

It is a happy number.

664864555680 is a `hidden beast` number, since 6 + 6 + 4 + 8 + 64 + 5 + 5 + 568 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 67817659 + ... + 67827461.

It is an arithmetic number, because the mean of its divisors is an integer number (8487156132).

Almost surely, 2^664864555680 is an apocalyptic number.

664864555680 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664864555680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1222150483008).

664864555680 is an abundant number, since it is smaller than the sum of its proper divisors (1779436410336).

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

664864555680 is a wasteful number, since it uses less digits than its factorization.

664864555680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13460 (or 13449 counting only the distinct ones).

The product of its (nonzero) digits is 165888000, while the sum is 63.

The spelling of 664864555680 in words is "six hundred sixty-four billion, eight hundred sixty-four million, five hundred fifty-five thousand, six hundred eighty".