665661166566 has 16 divisors (see below), whose sum is σ = 1452351636288. Its totient is φ = 201715505000.

The previous prime is 665661166529. The next prime is 665661166571.

665661166566 is nontrivially palindromic in base 10.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5042887560 + ... + 5042887691.

It is an arithmetic number, because the mean of its divisors is an integer number (90771977268).

Almost surely, 2^665661166566 is an apocalyptic number.

665661166566 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

665661166566 is an abundant number, since it is smaller than the sum of its proper divisors (786690469722).

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

665661166566 is a wasteful number, since it uses less digits than its factorization.

665661166566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10085775267.

The product of its digits is 41990400, while the sum is 60.

The spelling of 665661166566 in words is "six hundred sixty-five billion, six hundred sixty-one million, one hundred sixty-six thousand, five hundred sixty-six".