81039 has 16 divisors (see below), whose sum is σ = 131328. Its totient is φ = 43392.

The previous prime is 81031. The next prime is 81041. The reversal of 81039 is 93018.

It is not a de Polignac number, because 81039 - 2³ = 81031 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

81039 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81031) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 244 + ... + 470.

It is an arithmetic number, because the mean of its divisors is an integer number (8208).

2⁸¹⁰³⁹ is an apocalyptic number.

81039 is a deficient number, since it is larger than the sum of its proper divisors (50289).

81039 is a wasteful number, since it uses less digits than its factorization.

81039 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 254.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 81039 is about 284.6734971858. The cubic root of 81039 is about 43.2744301596.

Subtracting from 81039 its sum of digits (21), we obtain a palindrome (81018).

It can be divided in two parts, 8103 and 9, that multiplied together give a palindrome (72927).

The spelling of 81039 in words is "eighty-one thousand, thirty-nine".