166961909 has 2 divisors, whose sum is σ = 166961910. Its totient is φ = 166961908.

The previous prime is 166961891. The next prime is 166961933. The reversal of 166961909 is 909169661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 133864900 + 33097009 = 11570^2 + 5753^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166961909 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166961309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83480954 + 83480955.

It is an arithmetic number, because the mean of its divisors is an integer number (83480955).

Almost surely, 2^166961909 is an apocalyptic number.

It is an amenable number.

166961909 is a deficient number, since it is larger than the sum of its proper divisors (1).

166961909 is an equidigital number, since it uses as much as digits as its factorization.

166961909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 157464, while the sum is 47.

The square root of 166961909 is about 12921.3741142341. The cubic root of 166961909 is about 550.6459726912.

The spelling of 166961909 in words is "one hundred sixty-six million, nine hundred sixty-one thousand, nine hundred nine".