181997549 has 2 divisors, whose sum is σ = 181997550. Its totient is φ = 181997548.

The previous prime is 181997539. The next prime is 181997573. The reversal of 181997549 is 945799181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 113273449 + 68724100 = 10643^2 + 8290^2 .

It is a cyclic number.

It is not a de Polignac number, because 181997549 - 2²⁰ = 180948973 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 181997549.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181997539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90998774 + 90998775.

It is an arithmetic number, because the mean of its divisors is an integer number (90998775).

Almost surely, 2^181997549 is an apocalyptic number.

It is an amenable number.

181997549 is a deficient number, since it is larger than the sum of its proper divisors (1).

181997549 is an equidigital number, since it uses as much as digits as its factorization.

181997549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 816480, while the sum is 53.

The square root of 181997549 is about 13490.6467228224. The cubic root of 181997549 is about 566.7025668528.

The spelling of 181997549 in words is "one hundred eighty-one million, nine hundred ninety-seven thousand, five hundred forty-nine".