181839221 has 2 divisors, whose sum is σ = 181839222. Its totient is φ = 181839220.

The previous prime is 181839199. The next prime is 181839233. The reversal of 181839221 is 122938181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 171348100 + 10491121 = 13090^2 + 3239^2 .

It is a cyclic number.

It is not a de Polignac number, because 181839221 - 2¹⁰ = 181838197 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181839241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90919610 + 90919611.

It is an arithmetic number, because the mean of its divisors is an integer number (90919611).

Almost surely, 2^181839221 is an apocalyptic number.

It is an amenable number.

181839221 is a deficient number, since it is larger than the sum of its proper divisors (1).

181839221 is an equidigital number, since it uses as much as digits as its factorization.

181839221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6912, while the sum is 35.

The square root of 181839221 is about 13484.7773804390. Note that the first 3 decimals coincide. The cubic root of 181839221 is about 566.5381856736.

The spelling of 181839221 in words is "one hundred eighty-one million, eight hundred thirty-nine thousand, two hundred twenty-one".