809171985 has 16 divisors (see below), whose sum is σ = 1306777536. Its totient is φ = 427524288.

The previous prime is 809171983. The next prime is 809171989. The reversal of 809171985 is 589171908.

It is not a de Polignac number, because 809171985 - 2¹ = 809171983 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (809171983) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 250474 + ... + 253683.

It is an arithmetic number, because the mean of its divisors is an integer number (81673596).

Almost surely, 2^809171985 is an apocalyptic number.

It is an amenable number.

809171985 is a deficient number, since it is larger than the sum of its proper divisors (497605551).

809171985 is a wasteful number, since it uses less digits than its factorization.

809171985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 504272.

The product of its (nonzero) digits is 181440, while the sum is 48.

The square root of 809171985 is about 28445.9484812864. The cubic root of 809171985 is about 931.8520095260.

The spelling of 809171985 in words is "eight hundred nine million, one hundred seventy-one thousand, nine hundred eighty-five".