161520809 has 2 divisors, whose sum is σ = 161520810. Its totient is φ = 161520808.

The previous prime is 161520803. The next prime is 161520841. The reversal of 161520809 is 908025161.

It is an a-pointer prime, because the next prime (161520841) can be obtained adding 161520809 to its sum of digits (32).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 155625625 + 5895184 = 12475^2 + 2428^2 .

It is a cyclic number.

It is not a de Polignac number, because 161520809 - 2¹² = 161516713 is a prime.

It is not a weakly prime, because it can be changed into another prime (161520803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80760404 + 80760405.

It is an arithmetic number, because the mean of its divisors is an integer number (80760405).

Almost surely, 2^161520809 is an apocalyptic number.

It is an amenable number.

161520809 is a deficient number, since it is larger than the sum of its proper divisors (1).

161520809 is an equidigital number, since it uses as much as digits as its factorization.

161520809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 161520809 is about 12709.0837199225. The cubic root of 161520809 is about 544.5981483459.

The spelling of 161520809 in words is "one hundred sixty-one million, five hundred twenty thousand, eight hundred nine".