181664489 has 2 divisors, whose sum is σ = 181664490. Its totient is φ = 181664488.

The previous prime is 181664479. The next prime is 181664501. The reversal of 181664489 is 984466181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 105678400 + 75986089 = 10280^2 + 8717^2 .

It is an emirp because it is prime and its reverse (984466181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 181664489 - 2¹⁶ = 181598953 is a prime.

It is a super-2 number, since 2×181664489² = 66003973127262242, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (181664479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90832244 + 90832245.

It is an arithmetic number, because the mean of its divisors is an integer number (90832245).

Almost surely, 2^181664489 is an apocalyptic number.

It is an amenable number.

181664489 is a deficient number, since it is larger than the sum of its proper divisors (1).

181664489 is an equidigital number, since it uses as much as digits as its factorization.

181664489 is an evil number, because the sum of its binary digits is even.

The product of its digits is 331776, while the sum is 47.

The square root of 181664489 is about 13478.2969621536. The cubic root of 181664489 is about 566.3566625412.

The spelling of 181664489 in words is "one hundred eighty-one million, six hundred sixty-four thousand, four hundred eighty-nine".