161678189 has 2 divisors, whose sum is σ = 161678190. Its totient is φ = 161678188.

The previous prime is 161678141. The next prime is 161678191. The reversal of 161678189 is 981876161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 129846025 + 31832164 = 11395^2 + 5642^2 .

It is a cyclic number.

It is not a de Polignac number, because 161678189 - 2¹⁶ = 161612653 is a prime.

It is a super-2 number, since 2×161678189² = 52279673596639442, which contains 22 as substring.

Together with 161678191, it forms a pair of twin primes.

It is a Chen prime.

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

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161678989) 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, 80839094 + 80839095.

It is an arithmetic number, because the mean of its divisors is an integer number (80839095).

Almost surely, 2^161678189 is an apocalyptic number.

It is an amenable number.

161678189 is a deficient number, since it is larger than the sum of its proper divisors (1).

161678189 is an equidigital number, since it uses as much as digits as its factorization.

161678189 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145152, while the sum is 47.

The square root of 161678189 is about 12715.2738468348. The cubic root of 161678189 is about 544.7749698031.

The spelling of 161678189 in words is "one hundred sixty-one million, six hundred seventy-eight thousand, one hundred eighty-nine".