81243 has 20 divisors (see below), whose sum is σ = 130680. Its totient is φ = 50112.

The previous prime is 81239. The next prime is 81281. The reversal of 81243 is 34218.

It is a happy number.

It is not a de Polignac number, because 81243 - 2² = 81239 is a prime.

81243 is a modest number, since divided by 243 gives 81 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81203) 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 19 ways as a sum of consecutive naturals, for example, 1348 + ... + 1406.

It is an arithmetic number, because the mean of its divisors is an integer number (6534).

2⁸¹²⁴³ is an apocalyptic number.

81243 is a deficient number, since it is larger than the sum of its proper divisors (49437).

81243 is a wasteful number, since it uses less digits than its factorization.

81243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88 (or 79 counting only the distinct ones).

The product of its digits is 192, while the sum is 18.

The square root of 81243 is about 285.0315771980. The cubic root of 81243 is about 43.3107114008.

Subtracting from 81243 its sum of digits (18), we obtain a square (81225 = 285²).

It can be divided in two parts, 81 and 243, that multiplied together give a 9-th power (19683 = 3⁹).

The spelling of 81243 in words is "eighty-one thousand, two hundred forty-three".