666756657666 has 96 divisors (see below), whose sum is σ = 1592770832640. Its totient is φ = 199896576000.

The previous prime is 666756657661. The next prime is 666756657667.

666756657666 is nontrivially palindromic in base 10.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 666756657594 and 666756657603.

It is not an unprimeable number, because it can be changed into a prime (666756657661) by changing a digit.

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, 28165351 + ... + 28189013.

It is an arithmetic number, because the mean of its divisors is an integer number (16591362840).

Almost surely, 2^666756657666 is an apocalyptic number.

666756657666 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 666756657666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (796385416320).

666756657666 is an abundant number, since it is smaller than the sum of its proper divisors (926014174974).

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

666756657666 is a wasteful number, since it uses less digits than its factorization.

666756657666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25192 (or 25189 counting only the distinct ones).

The product of its digits is 2057529600, while the sum is 72.

The spelling of 666756657666 in words is "six hundred sixty-six billion, seven hundred fifty-six million, six hundred fifty-seven thousand, six hundred sixty-six".