165161561 has 2 divisors, whose sum is σ = 165161562. Its totient is φ = 165161560.

The previous prime is 165161537. The next prime is 165161593.

165161561 is nontrivially palindromic in base 10.

It is an a-pointer prime, because the next prime (165161593) can be obtained adding 165161561 to its sum of digits (32).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 162817600 + 2343961 = 12760^2 + 1531^2 .

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 165161561 - 2¹⁰ = 165160537 is a prime.

It is not a weakly prime, because it can be changed into another prime (165161531) 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 as a sum of consecutive naturals, namely, 82580780 + 82580781.

It is an arithmetic number, because the mean of its divisors is an integer number (82580781).

Almost surely, 2^165161561 is an apocalyptic number.

It is an amenable number.

165161561 is a deficient number, since it is larger than the sum of its proper divisors (1).

165161561 is an equidigital number, since it uses as much as digits as its factorization.

165161561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5400, while the sum is 32.

The square root of 165161561 is about 12851.5197933941. The cubic root of 165161561 is about 548.6596131762.

The spelling of 165161561 in words is "one hundred sixty-five million, one hundred sixty-one thousand, five hundred sixty-one".