161665289 has 8 divisors (see below), whose sum is σ = 167370240. Its totient is φ = 156054816.

The previous prime is 161665271. The next prime is 161665307. The reversal of 161665289 is 982566161.

It is an interprime number because it is at equal distance from previous prime (161665271) and next prime (161665307).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161665289 - 2⁸ = 161665033 is a prime.

It is a super-2 number, since 2×161665289² = 52271331334907042, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161665249) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20129 + ... + 26990.

It is an arithmetic number, because the mean of its divisors is an integer number (20921280).

Almost surely, 2^161665289 is an apocalyptic number.

It is an amenable number.

161665289 is a deficient number, since it is larger than the sum of its proper divisors (5704951).

161665289 is an equidigital number, since it uses as much as digits as its factorization.

161665289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47239.

The product of its digits is 155520, while the sum is 44.

The square root of 161665289 is about 12714.7665727688. The cubic root of 161665289 is about 544.7604805594.

The spelling of 161665289 in words is "one hundred sixty-one million, six hundred sixty-five thousand, two hundred eighty-nine".