161993609 has 2 divisors, whose sum is σ = 161993610. Its totient is φ = 161993608.

The previous prime is 161993593. The next prime is 161993627. The reversal of 161993609 is 906399161.

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., 122655625 + 39337984 = 11075^2 + 6272^2 .

It is a cyclic number.

It is not a de Polignac number, because 161993609 - 2⁴ = 161993593 is a prime.

It is a Sophie Germain prime.

It is a Chen 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 161993609.

It is not a weakly prime, because it can be changed into another prime (161993509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80996804 + 80996805.

It is an arithmetic number, because the mean of its divisors is an integer number (80996805).

Almost surely, 2^161993609 is an apocalyptic number.

It is an amenable number.

161993609 is a deficient number, since it is larger than the sum of its proper divisors (1).

161993609 is an equidigital number, since it uses as much as digits as its factorization.

161993609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 78732, while the sum is 44.

The square root of 161993609 is about 12727.6709966906. The cubic root of 161993609 is about 545.1290091025.

The spelling of 161993609 in words is "one hundred sixty-one million, nine hundred ninety-three thousand, six hundred nine".