81838013 has 2 divisors, whose sum is σ = 81838014. Its totient is φ = 81838012.

The previous prime is 81838007. The next prime is 81838019. The reversal of 81838013 is 31083818.

It is a balanced prime because it is at equal distance from previous prime (81838007) and next prime (81838019).

It can be written as a sum of positive squares in only one way, i.e., 78889924 + 2948089 = 8882^2 + 1717^2 .

It is a cyclic number.

It is not a de Polignac number, because 81838013 - 2⁸ = 81837757 is a prime.

It is equal to p_4770491 and since 81838013 and 4770491 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81838019) 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, 40919006 + 40919007.

It is an arithmetic number, because the mean of its divisors is an integer number (40919007).

Almost surely, 2^81838013 is an apocalyptic number.

It is an amenable number.

81838013 is a deficient number, since it is larger than the sum of its proper divisors (1).

81838013 is an equidigital number, since it uses as much as digits as its factorization.

81838013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 81838013 is about 9046.4364807365. The cubic root of 81838013 is about 434.1618829511.

The spelling of 81838013 in words is "eighty-one million, eight hundred thirty-eight thousand, thirteen".