81369 has 6 divisors (see below), whose sum is σ = 117546. Its totient is φ = 54240.

The previous prime is 81359. The next prime is 81371. The reversal of 81369 is 96318.

It can be written as a sum of positive squares in only one way, i.e., 81225 + 144 = 285^2 + 12^2 .

It is not a de Polignac number, because 81369 - 2⁴ = 81353 is a prime.

It is a super-2 number, since 2×81369² = 13241828322, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81349) 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 5 ways as a sum of consecutive naturals, for example, 4512 + ... + 4529.

It is an arithmetic number, because the mean of its divisors is an integer number (19591).

2⁸¹³⁶⁹ is an apocalyptic number.

It is an amenable number.

81369 is a deficient number, since it is larger than the sum of its proper divisors (36177).

81369 is a wasteful number, since it uses less digits than its factorization.

81369 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9047 (or 9044 counting only the distinct ones).

The product of its digits is 1296, while the sum is 27.

The square root of 81369 is about 285.2525197084. The cubic root of 81369 is about 43.3330900710. Note that the first 3 decimals are identical.

The spelling of 81369 in words is "eighty-one thousand, three hundred sixty-nine".