81539279 has 8 divisors (see below), whose sum is σ = 85987440. Its totient is φ = 77106816.

The previous prime is 81539273. The next prime is 81539291. The reversal of 81539279 is 97293518.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81539279 - 2²⁰ = 80490703 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81539273) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7649 + ... + 14885.

It is an arithmetic number, because the mean of its divisors is an integer number (10748430).

Almost surely, 2^81539279 is an apocalyptic number.

81539279 is a deficient number, since it is larger than the sum of its proper divisors (4448161).

81539279 is a wasteful number, since it uses less digits than its factorization.

81539279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7849.

The product of its digits is 136080, while the sum is 44.

The square root of 81539279 is about 9029.9102431863. The cubic root of 81539279 is about 433.6329639085.

It can be divided in two parts, 81539 and 279, that added together give a palindrome (81818).

The spelling of 81539279 in words is "eighty-one million, five hundred thirty-nine thousand, two hundred seventy-nine".