81668952666 has 48 divisors (see below), whose sum is σ = 202278148800. Its totient is φ = 23328186624.

The previous prime is 81668952643. The next prime is 81668952709. The reversal of 81668952666 is 66625986618.

It is a super-2 number, since 2×81668952666² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

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 23 ways as a sum of consecutive naturals, for example, 441765 + ... + 598743.

It is an arithmetic number, because the mean of its divisors is an integer number (4214128100).

Almost surely, 2^81668952666 is an apocalyptic number.

81668952666 is an abundant number, since it is smaller than the sum of its proper divisors (120609196134).

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

81668952666 is a wasteful number, since it uses less digits than its factorization.

81668952666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161123 (or 161120 counting only the distinct ones).

The product of its digits is 44789760, while the sum is 63.

The spelling of 81668952666 in words is "eighty-one billion, six hundred sixty-eight million, nine hundred fifty-two thousand, six hundred sixty-six".