169991009 has 2 divisors, whose sum is σ = 169991010. Its totient is φ = 169991008.

The previous prime is 169990943. The next prime is 169991021. The reversal of 169991009 is 900199961.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 87235600 + 82755409 = 9340^2 + 9097^2 .

It is a cyclic number.

It is not a de Polignac number, because 169991009 - 2⁸ = 169990753 is a prime.

It is not a weakly prime, because it can be changed into another prime (169991039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84995504 + 84995505.

It is an arithmetic number, because the mean of its divisors is an integer number (84995505).

Almost surely, 2^169991009 is an apocalyptic number.

It is an amenable number.

169991009 is a deficient number, since it is larger than the sum of its proper divisors (1).

169991009 is an equidigital number, since it uses as much as digits as its factorization.

169991009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 39366, while the sum is 44.

The square root of 169991009 is about 13038.0600167356. The cubic root of 169991009 is about 553.9560594116.

The spelling of 169991009 in words is "one hundred sixty-nine million, nine hundred ninety-one thousand, nine".