809605220161 has 4 divisors (see below), whose sum is σ = 810549917892. Its totient is φ = 808660522432.

The previous prime is 809605220089. The next prime is 809605220167. The reversal of 809605220161 is 161022506908.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 636116309761 + 173488910400 = 797569^2 + 416520^2 .

It is a cyclic number.

It is not a de Polignac number, because 809605220161 - 2¹⁵ = 809605187393 is a prime.

It is a super-2 number, since 2×809605220161² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (809605220167) 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 in 3 ways as a sum of consecutive naturals, for example, 472347580 + ... + 472349293.

It is an arithmetic number, because the mean of its divisors is an integer number (202637479473).

Almost surely, 2^809605220161 is an apocalyptic number.

It is an amenable number.

809605220161 is a deficient number, since it is larger than the sum of its proper divisors (944697731).

809605220161 is an equidigital number, since it uses as much as digits as its factorization.

809605220161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 944697730.

The product of its (nonzero) digits is 51840, while the sum is 40.

The spelling of 809605220161 in words is "eight hundred nine billion, six hundred five million, two hundred twenty thousand, one hundred sixty-one".