166561660667 has 4 divisors (see below), whose sum is σ = 175328063880. Its totient is φ = 157795257456.

The previous prime is 166561660663. The next prime is 166561660669. The reversal of 166561660667 is 766066165661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 166561660667 - 2² = 166561660663 is a prime.

It is a Duffinian number.

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, 4383201578 + ... + 4383201615.

It is an arithmetic number, because the mean of its divisors is an integer number (43832015970).

Almost surely, 2^166561660667 is an apocalyptic number.

166561660667 is a deficient number, since it is larger than the sum of its proper divisors (8766403213).

166561660667 is an equidigital number, since it uses as much as digits as its factorization.

166561660667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8766403212.

The product of its (nonzero) digits is 9797760, while the sum is 56.

The spelling of 166561660667 in words is "one hundred sixty-six billion, five hundred sixty-one million, six hundred sixty thousand, six hundred sixty-seven".