66681018666 has 32 divisors (see below), whose sum is σ = 151332814080. Its totient is φ = 21754090368.

The previous prime is 66681018653. The next prime is 66681018673.

66681018666 is nontrivially palindromic in base 10.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13133991 + ... + 13139066.

It is an arithmetic number, because the mean of its divisors is an integer number (4729150440).

Almost surely, 2^66681018666 is an apocalyptic number.

66681018666 is an abundant number, since it is smaller than the sum of its proper divisors (84651795414).

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

66681018666 is a wasteful number, since it uses less digits than its factorization.

66681018666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26273115 (or 26273109 counting only the distinct ones).

The product of its (nonzero) digits is 2985984, while the sum is 54.

The spelling of 66681018666 in words is "sixty-six billion, six hundred eighty-one million, eighteen thousand, six hundred sixty-six".