181213 has 2 divisors, whose sum is σ = 181214. Its totient is φ = 181212.

The previous prime is 181211. The next prime is 181219. The reversal of 181213 is 312181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 101124 + 80089 = 318^2 + 283^2 .

It is a cyclic number.

It is not a de Polignac number, because 181213 - 2¹ = 181211 is a prime.

Together with 181211, it forms a pair of twin primes.

181213 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90606 + 90607.

It is an arithmetic number, because the mean of its divisors is an integer number (90607).

2¹⁸¹²¹³ is an apocalyptic number.

It is an amenable number.

181213 is a deficient number, since it is larger than the sum of its proper divisors (1).

181213 is an equidigital number, since it uses as much as digits as its factorization.

181213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48, while the sum is 16.

The square root of 181213 is about 425.6912026340. The cubic root of 181213 is about 56.5887086401.

Adding to 181213 its reverse (312181), we get a palindrome (493394).

The spelling of 181213 in words is "one hundred eighty-one thousand, two hundred thirteen".