666681494856 has 256 divisors, whose sum is σ = 1891064448000. Its totient is φ = 194434007040.

The previous prime is 666681494819. The next prime is 666681494867. The reversal of 666681494856 is 658494186666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 129374776 + ... + 129379928.

It is an arithmetic number, because the mean of its divisors is an integer number (7386970500).

Almost surely, 2^666681494856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666681494856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (945532224000).

666681494856 is an abundant number, since it is smaller than the sum of its proper divisors (1224382953144).

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

666681494856 is a wasteful number, since it uses less digits than its factorization.

666681494856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5464 (or 5460 counting only the distinct ones).

The product of its digits is 358318080, while the sum is 69.

The spelling of 666681494856 in words is "six hundred sixty-six billion, six hundred eighty-one million, four hundred ninety-four thousand, eight hundred fifty-six".