165561289 has 2 divisors, whose sum is σ = 165561290. Its totient is φ = 165561288.

The previous prime is 165561287. The next prime is 165561293. The reversal of 165561289 is 982165561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 165559689 + 1600 = 12867^2 + 40^2 .

It is a cyclic number.

It is not a de Polignac number, because 165561289 - 2¹ = 165561287 is a prime.

Together with 165561287, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (165561287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82780644 + 82780645.

It is an arithmetic number, because the mean of its divisors is an integer number (82780645).

Almost surely, 2^165561289 is an apocalyptic number.

It is an amenable number.

165561289 is a deficient number, since it is larger than the sum of its proper divisors (1).

165561289 is an equidigital number, since it uses as much as digits as its factorization.

165561289 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 129600, while the sum is 43.

The square root of 165561289 is about 12867.0621744048. The cubic root of 165561289 is about 549.1018829874.

The spelling of 165561289 in words is "one hundred sixty-five million, five hundred sixty-one thousand, two hundred eighty-nine".