81539171 has 4 divisors (see below), whose sum is σ = 93187632. Its totient is φ = 69890712.

The previous prime is 81539147. The next prime is 81539173. The reversal of 81539171 is 17193518.

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 81539171 - 2²⁶ = 14430307 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81539173) 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, 5824220 + ... + 5824233.

It is an arithmetic number, because the mean of its divisors is an integer number (23296908).

Almost surely, 2^81539171 is an apocalyptic number.

81539171 is a deficient number, since it is larger than the sum of its proper divisors (11648461).

81539171 is a wasteful number, since it uses less digits than its factorization.

81539171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11648460.

The product of its digits is 7560, while the sum is 35.

The square root of 81539171 is about 9029.9042630584. The cubic root of 81539171 is about 433.6327724573.

The spelling of 81539171 in words is "eighty-one million, five hundred thirty-nine thousand, one hundred seventy-one".