166561660671 has 32 divisors (see below), whose sum is σ = 254196154368. Its totient is φ = 95032771680.

The previous prime is 166561660669. The next prime is 166561660691. The reversal of 166561660671 is 176066165661.

It is a happy number.

It is not a de Polignac number, because 166561660671 - 2¹ = 166561660669 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166561660651) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 65496826 + ... + 65499368.

It is an arithmetic number, because the mean of its divisors is an integer number (7943629824).

Almost surely, 2^166561660671 is an apocalyptic number.

166561660671 is a deficient number, since it is larger than the sum of its proper divisors (87634493697).

166561660671 is a wasteful number, since it uses less digits than its factorization.

166561660671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6091.

The product of its (nonzero) digits is 1632960, while the sum is 51.

The spelling of 166561660671 in words is "one hundred sixty-six billion, five hundred sixty-one million, six hundred sixty thousand, six hundred seventy-one".