12165561 has 12 divisors (see below), whose sum is σ = 18001620. Its totient is φ = 7912320.

The previous prime is 12165497. The next prime is 12165581. The reversal of 12165561 is 16556121.

It is a happy number.

12165561 is a `hidden beast` number, since 1 + 2 + 1 + 655 + 6 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 2205225 + 9960336 = 1485^2 + 3156^2 .

It is not a de Polignac number, because 12165561 - 2⁶ = 12165497 is a prime.

It is not an unprimeable number, because it can be changed into a prime (12165581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16116 + ... + 16853.

It is an arithmetic number, because the mean of its divisors is an integer number (1500135).

Almost surely, 2^12165561 is an apocalyptic number.

It is an amenable number.

12165561 is a deficient number, since it is larger than the sum of its proper divisors (5836059).

12165561 is a wasteful number, since it uses less digits than its factorization.

12165561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33016 (or 33013 counting only the distinct ones).

The product of its digits is 1800, while the sum is 27.

The square root of 12165561 is about 3487.9164267511. The cubic root of 12165561 is about 229.9909322197.

The spelling of 12165561 in words is "twelve million, one hundred sixty-five thousand, five hundred sixty-one".