161964809 has 2 divisors, whose sum is σ = 161964810. Its totient is φ = 161964808.

The previous prime is 161964793. The next prime is 161964823. The reversal of 161964809 is 908469161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 122589184 + 39375625 = 11072^2 + 6275^2 .

It is a cyclic number.

It is not a de Polignac number, because 161964809 - 2⁴ = 161964793 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 161964809.

It is not a weakly prime, because it can be changed into another prime (161964839) 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, 80982404 + 80982405.

It is an arithmetic number, because the mean of its divisors is an integer number (80982405).

Almost surely, 2^161964809 is an apocalyptic number.

It is an amenable number.

161964809 is a deficient number, since it is larger than the sum of its proper divisors (1).

161964809 is an equidigital number, since it uses as much as digits as its factorization.

161964809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 93312, while the sum is 44.

The square root of 161964809 is about 12726.5395532328. The cubic root of 161964809 is about 545.0967019721.

The spelling of 161964809 in words is "one hundred sixty-one million, nine hundred sixty-four thousand, eight hundred nine".