161558809 has 4 divisors (see below), whose sum is σ = 162588004. Its totient is φ = 160529616.

The previous prime is 161558807. The next prime is 161558821. The reversal of 161558809 is 908855161.

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 120560400 + 40998409 = 10980^2 + 6403^2 .

It is a cyclic number.

It is not a de Polignac number, because 161558809 - 2¹ = 161558807 is a prime.

It is a super-2 number, since 2×161558809² = 52202497530996962, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161558801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 514362 + ... + 514675.

It is an arithmetic number, because the mean of its divisors is an integer number (40647001).

Almost surely, 2^161558809 is an apocalyptic number.

It is an amenable number.

161558809 is a deficient number, since it is larger than the sum of its proper divisors (1029195).

161558809 is a wasteful number, since it uses less digits than its factorization.

161558809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1029194.

The product of its (nonzero) digits is 86400, while the sum is 43.

The square root of 161558809 is about 12710.5786256960. The cubic root of 161558809 is about 544.6408530745.

It can be divided in two parts, 16155 and 8809, that added together give a square (24964 = 158²).

The spelling of 161558809 in words is "one hundred sixty-one million, five hundred fifty-eight thousand, eight hundred nine".