664636768686 has 160 divisors (see below), whose sum is σ = 1645760083968. Its totient is φ = 198803108160.

The previous prime is 664636768681. The next prime is 664636768703. The reversal of 664636768686 is 686867636466.

664636768686 is a `hidden beast` number, since 6 + 6 + 463 + 6 + 7 + 6 + 86 + 86 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664636768681) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 58178371 + ... + 58189793.

Almost surely, 2^664636768686 is an apocalyptic number.

664636768686 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 664636768686, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (822880041984).

664636768686 is an abundant number, since it is smaller than the sum of its proper divisors (981123315282).

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

664636768686 is a wasteful number, since it uses less digits than its factorization.

664636768686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11868 (or 11859 counting only the distinct ones).

The product of its digits is 1504935936, while the sum is 72.

The spelling of 664636768686 in words is "six hundred sixty-four billion, six hundred thirty-six million, seven hundred sixty-eight thousand, six hundred eighty-six".