81539 has 4 divisors (see below), whose sum is σ = 82824. Its totient is φ = 80256.

The previous prime is 81533. The next prime is 81547. The reversal of 81539 is 93518.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81539 - 2⁸ = 81283 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 81539.

It is not an unprimeable number, because it can be changed into a prime (81533) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 542 + ... + 675.

It is an arithmetic number, because the mean of its divisors is an integer number (20706).

2⁸¹⁵³⁹ is an apocalyptic number.

81539 is a deficient number, since it is larger than the sum of its proper divisors (1285).

81539 is a wasteful number, since it uses less digits than its factorization.

81539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1284.

The product of its digits is 1080, while the sum is 26.

The square root of 81539 is about 285.5503458236. The cubic root of 81539 is about 43.3632469326.

The spelling of 81539 in words is "eighty-one thousand, five hundred thirty-nine".