81839 has 2 divisors, whose sum is σ = 81840. Its totient is φ = 81838.

The previous prime is 81817. The next prime is 81847. The reversal of 81839 is 93818.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81839 - 2¹² = 77743 is a prime.

It is a Sophie Germain 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 (81869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40919 + 40920.

It is an arithmetic number, because the mean of its divisors is an integer number (40920).

2⁸¹⁸³⁹ is an apocalyptic number.

81839 is a deficient number, since it is larger than the sum of its proper divisors (1).

81839 is an equidigital number, since it uses as much as digits as its factorization.

81839 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1728, while the sum is 29.

The square root of 81839 is about 286.0751649480. The cubic root of 81839 is about 43.4163628334.

Subtracting from 81839 its sum of digits (29), we obtain a triangular number (81810 = T₄₀₄).

It can be divided in two parts, 8183 and 9, that added together give a 13-th power (8192 = 2¹³).

The spelling of 81839 in words is "eighty-one thousand, eight hundred thirty-nine".