181899181 has 2 divisors, whose sum is σ = 181899182. Its totient is φ = 181899180.

The previous prime is 181899161. The next prime is 181899187. The reversal of 181899181 is 181998181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 173343556 + 8555625 = 13166^2 + 2925^2 .

It is an emirp because it is prime and its reverse (181998181) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-181899181 is a prime.

It is a super-2 number, since 2×181899181² = 66174624096941522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181899187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90949590 + 90949591.

It is an arithmetic number, because the mean of its divisors is an integer number (90949591).

Almost surely, 2^181899181 is an apocalyptic number.

It is an amenable number.

181899181 is a deficient number, since it is larger than the sum of its proper divisors (1).

181899181 is an equidigital number, since it uses as much as digits as its factorization.

181899181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 46.

The square root of 181899181 is about 13487.0004448728. Note that the first 3 decimals coincide. The cubic root of 181899181 is about 566.6004492791.

The spelling of 181899181 in words is "one hundred eighty-one million, eight hundred ninety-nine thousand, one hundred eighty-one".