165898561 has 2 divisors, whose sum is σ = 165898562. Its totient is φ = 165898560.

The previous prime is 165898553. The next prime is 165898571.

165898561 is nontrivially palindromic in base 10.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 87310336 + 78588225 = 9344^2 + 8865^2 .

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 165898561 - 2³ = 165898553 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is not a weakly prime, because it can be changed into another prime (165898511) 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, 82949280 + 82949281.

It is an arithmetic number, because the mean of its divisors is an integer number (82949281).

Almost surely, 2^165898561 is an apocalyptic number.

It is an amenable number.

165898561 is a deficient number, since it is larger than the sum of its proper divisors (1).

165898561 is an equidigital number, since it uses as much as digits as its factorization.

165898561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 518400, while the sum is 49.

The square root of 165898561 is about 12880.1615284902. The cubic root of 165898561 is about 549.4744964088.

The spelling of 165898561 in words is "one hundred sixty-five million, eight hundred ninety-eight thousand, five hundred sixty-one".