81841 has 4 divisors (see below), whose sum is σ = 82432. Its totient is φ = 81252.

The previous prime is 81839. The next prime is 81847. The reversal of 81841 is 14818.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 81841 - 2¹ = 81839 is a prime.

It is a Duffinian number.

81841 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (81847) 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 in 3 ways as a sum of consecutive naturals, for example, 40 + ... + 406.

It is an arithmetic number, because the mean of its divisors is an integer number (20608).

2⁸¹⁸⁴¹ is an apocalyptic number.

It is an amenable number.

81841 is a deficient number, since it is larger than the sum of its proper divisors (591).

81841 is a wasteful number, since it uses less digits than its factorization.

81841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 590.

The product of its digits is 256, while the sum is 22.

The square root of 81841 is about 286.0786605114. The cubic root of 81841 is about 43.4167165035.

It can be divided in two parts, 81 and 841, that multiplied together give a square (68121 = 261²).

The spelling of 81841 in words is "eighty-one thousand, eight hundred forty-one".