166561660666 has 8 divisors (see below), whose sum is σ = 249971881824. Its totient is φ = 83237700060.

The previous prime is 166561660663. The next prime is 166561660669. The reversal of 166561660666 is 666066165661.

It is an interprime number because it is at equal distance from previous prime (166561660663) and next prime (166561660669).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (166561660663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21560310 + ... + 21568033.

It is an arithmetic number, because the mean of its divisors is an integer number (31246485228).

Almost surely, 2^166561660666 is an apocalyptic number.

166561660666 is a deficient number, since it is larger than the sum of its proper divisors (83410221158).

166561660666 is a wasteful number, since it uses less digits than its factorization.

166561660666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43130276.

The product of its (nonzero) digits is 8398080, while the sum is 55.

The spelling of 166561660666 in words is "one hundred sixty-six billion, five hundred sixty-one million, six hundred sixty thousand, six hundred sixty-six".