166581185689 has 2 divisors, whose sum is σ = 166581185690. Its totient is φ = 166581185688.

The previous prime is 166581185657. The next prime is 166581185699. The reversal of 166581185689 is 986581185661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155157210000 + 11423975689 = 393900^2 + 106883^2 .

It is a cyclic number.

It is not a de Polignac number, because 166581185689 - 2⁵ = 166581185657 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 166581185689.

It is not a weakly prime, because it can be changed into another prime (166581185699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83290592844 + 83290592845.

It is an arithmetic number, because the mean of its divisors is an integer number (83290592845).

Almost surely, 2^166581185689 is an apocalyptic number.

It is an amenable number.

166581185689 is a deficient number, since it is larger than the sum of its proper divisors (1).

166581185689 is an equidigital number, since it uses as much as digits as its factorization.

166581185689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24883200, while the sum is 64.

The spelling of 166581185689 in words is "one hundred sixty-six billion, five hundred eighty-one million, one hundred eighty-five thousand, six hundred eighty-nine".