8171205509 has 2 divisors, whose sum is σ = 8171205510. Its totient is φ = 8171205508.

The previous prime is 8171205491. The next prime is 8171205521. The reversal of 8171205509 is 9055021718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5296637284 + 2874568225 = 72778^2 + 53615^2 .

It is a cyclic number.

It is not a de Polignac number, because 8171205509 - 2¹² = 8171201413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8171205589) 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, 4085602754 + 4085602755.

It is an arithmetic number, because the mean of its divisors is an integer number (4085602755).

Almost surely, 2^8171205509 is an apocalyptic number.

It is an amenable number.

8171205509 is a deficient number, since it is larger than the sum of its proper divisors (1).

8171205509 is an equidigital number, since it uses as much as digits as its factorization.

8171205509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25200, while the sum is 38.

The square root of 8171205509 is about 90394.7205814587. The cubic root of 8171205509 is about 2014.1665433500.

The spelling of 8171205509 in words is "eight billion, one hundred seventy-one million, two hundred five thousand, five hundred nine".