166671809 has 2 divisors, whose sum is σ = 166671810. Its totient is φ = 166671808.

The previous prime is 166671797. The next prime is 166671829. The reversal of 166671809 is 908176661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 113891584 + 52780225 = 10672^2 + 7265^2 .

It is a cyclic number.

It is not a de Polignac number, because 166671809 - 2⁴ = 166671793 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 166671809.

It is not a weakly prime, because it can be changed into another prime (166671829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83335904 + 83335905.

It is an arithmetic number, because the mean of its divisors is an integer number (83335905).

Almost surely, 2^166671809 is an apocalyptic number.

It is an amenable number.

166671809 is a deficient number, since it is larger than the sum of its proper divisors (1).

166671809 is an equidigital number, since it uses as much as digits as its factorization.

166671809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108864, while the sum is 44.

The square root of 166671809 is about 12910.1436475355. The cubic root of 166671809 is about 550.3268679611.

The spelling of 166671809 in words is "one hundred sixty-six million, six hundred seventy-one thousand, eight hundred nine".