81864229 has 2 divisors, whose sum is σ = 81864230. Its totient is φ = 81864228.

The previous prime is 81864227. The next prime is 81864253. The reversal of 81864229 is 92246818.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77475204 + 4389025 = 8802^2 + 2095^2 .

It is a cyclic number.

It is not a de Polignac number, because 81864229 - 2¹ = 81864227 is a prime.

Together with 81864227, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 81864191 and 81864200.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81864221) 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, 40932114 + 40932115.

It is an arithmetic number, because the mean of its divisors is an integer number (40932115).

Almost surely, 2^81864229 is an apocalyptic number.

It is an amenable number.

81864229 is a deficient number, since it is larger than the sum of its proper divisors (1).

81864229 is an equidigital number, since it uses as much as digits as its factorization.

81864229 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 55296, while the sum is 40.

The square root of 81864229 is about 9047.8853330488. The cubic root of 81864229 is about 434.2082378269.

The spelling of 81864229 in words is "eighty-one million, eight hundred sixty-four thousand, two hundred twenty-nine".