166581185661 has 32 divisors (see below), whose sum is σ = 269273548800. Its totient is φ = 100939008240.

The previous prime is 166581185657. The next prime is 166581185689.

It is a happy number.

166581185661 is a `hidden beast` number, since 1 + 6 + 6 + 581 + 1 + 8 + 56 + 6 + 1 = 666.

166581185661 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 166581185661 - 2² = 166581185657 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 166581185598 and 166581185607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166581185611) 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, 1588330 + ... + 1689956.

It is an arithmetic number, because the mean of its divisors is an integer number (8414798400).

Almost surely, 2^166581185661 is an apocalyptic number.

166581185661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

166581185661 is a deficient number, since it is larger than the sum of its proper divisors (102692363139).

166581185661 is a wasteful number, since it uses less digits than its factorization.

166581185661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107166 (or 107160 counting only the distinct ones).

The product of its digits is 2073600, while the sum is 54.

The spelling of 166581185661 in words is "one hundred sixty-six billion, five hundred eighty-one million, one hundred eighty-five thousand, six hundred sixty-one".