165545561 has 4 divisors (see below), whose sum is σ = 165905124. Its totient is φ = 165186000.

The previous prime is 165545539. The next prime is 165545573.

It is a happy number.

165545561 is nontrivially palindromic in base 10.

165545561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 68641225 + 96904336 = 8285^2 + 9844^2 .

It is a cyclic number.

It is not a de Polignac number, because 165545561 - 2¹⁰ = 165544537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165545581) 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, 179090 + ... + 180011.

It is an arithmetic number, because the mean of its divisors is an integer number (41476281).

Almost surely, 2^165545561 is an apocalyptic number.

It is an amenable number.

165545561 is a deficient number, since it is larger than the sum of its proper divisors (359563).

165545561 is an equidigital number, since it uses as much as digits as its factorization.

165545561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 359562.

The product of its digits is 90000, while the sum is 38.

The square root of 165545561 is about 12866.4509869661. The cubic root of 165545561 is about 549.0844945669.

The spelling of 165545561 in words is "one hundred sixty-five million, five hundred forty-five thousand, five hundred sixty-one".