161578609 has 4 divisors (see below), whose sum is σ = 164627316. Its totient is φ = 158529904.

The previous prime is 161578597. The next prime is 161578619. The reversal of 161578609 is 906875161.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 906875161 = 27437 ⋅33053.

It can be written as a sum of positive squares in 2 ways, for example, as 51265600 + 110313009 = 7160^2 + 10503^2 .

It is a cyclic number.

It is not a de Polignac number, because 161578609 - 2⁵ = 161578577 is a prime.

It is a super-2 number, since 2×161578609² = 52215293772749762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161578619) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1524274 + ... + 1524379.

It is an arithmetic number, because the mean of its divisors is an integer number (41156829).

Almost surely, 2^161578609 is an apocalyptic number.

It is an amenable number.

161578609 is a deficient number, since it is larger than the sum of its proper divisors (3048707).

161578609 is an equidigital number, since it uses as much as digits as its factorization.

161578609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3048706.

The product of its (nonzero) digits is 90720, while the sum is 43.

The square root of 161578609 is about 12711.3574806155. The cubic root of 161578609 is about 544.6631018322.

The spelling of 161578609 in words is "one hundred sixty-one million, five hundred seventy-eight thousand, six hundred nine".