81686339 has 8 divisors (see below), whose sum is σ = 98269440. Its totient is φ = 66331656.

The previous prime is 81686321. The next prime is 81686347. The reversal of 81686339 is 93368618.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81686339 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81686339.

It is not an unprimeable number, because it can be changed into a prime (81686389) 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, 306959 + ... + 307224.

It is an arithmetic number, because the mean of its divisors is an integer number (12283680).

Almost surely, 2^81686339 is an apocalyptic number.

81686339 is a deficient number, since it is larger than the sum of its proper divisors (16583101).

81686339 is a wasteful number, since it uses less digits than its factorization.

81686339 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 614209.

The product of its digits is 186624, while the sum is 44.

The square root of 81686339 is about 9038.0495130310. The cubic root of 81686339 is about 433.8934999568.

The spelling of 81686339 in words is "eighty-one million, six hundred eighty-six thousand, three hundred thirty-nine".