166861889 has 2 divisors, whose sum is σ = 166861890. Its totient is φ = 166861888.

The previous prime is 166861883. The next prime is 166861927. The reversal of 166861889 is 988168661.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 114661264 + 52200625 = 10708^2 + 7225^2 .

It is a cyclic number.

It is not a de Polignac number, because 166861889 - 2⁴ = 166861873 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 166861889.

It is not a weakly prime, because it can be changed into another prime (166861883) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83430944 + 83430945.

It is an arithmetic number, because the mean of its divisors is an integer number (83430945).

Almost surely, 2^166861889 is an apocalyptic number.

It is an amenable number.

166861889 is a deficient number, since it is larger than the sum of its proper divisors (1).

166861889 is an equidigital number, since it uses as much as digits as its factorization.

166861889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 995328, while the sum is 53.

The square root of 166861889 is about 12917.5032030188. The cubic root of 166861889 is about 550.5359942895.

The spelling of 166861889 in words is "one hundred sixty-six million, eight hundred sixty-one thousand, eight hundred eighty-nine".