165844561 has 2 divisors, whose sum is σ = 165844562. Its totient is φ = 165844560.

The previous prime is 165844519. The next prime is 165844583. The reversal of 165844561 is 165448561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 164634561 + 1210000 = 12831^2 + 1100^2 .

It is a cyclic number.

It is not a de Polignac number, because 165844561 - 2¹⁷ = 165713489 is a prime.

It is not a weakly prime, because it can be changed into another prime (165844501) by changing a digit.

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

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82922280 + 82922281.

It is an arithmetic number, because the mean of its divisors is an integer number (82922281).

Almost surely, 2^165844561 is an apocalyptic number.

It is an amenable number.

165844561 is a deficient number, since it is larger than the sum of its proper divisors (1).

165844561 is an equidigital number, since it uses as much as digits as its factorization.

165844561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 115200, while the sum is 40.

The square root of 165844561 is about 12878.0651108775. The cubic root of 165844561 is about 549.4148719359.

The spelling of 165844561 in words is "one hundred sixty-five million, eight hundred forty-four thousand, five hundred sixty-one".