81384839 has 4 divisors (see below), whose sum is σ = 82920456. Its totient is φ = 79849224.

The previous prime is 81384811. The next prime is 81384841. The reversal of 81384839 is 93848318.

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 81384839 - 2²⁴ = 64607623 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 81384839.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81384869) 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, 767729 + ... + 767834.

It is an arithmetic number, because the mean of its divisors is an integer number (20730114).

Almost surely, 2^81384839 is an apocalyptic number.

81384839 is a deficient number, since it is larger than the sum of its proper divisors (1535617).

81384839 is a wasteful number, since it uses less digits than its factorization.

81384839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1535616.

The product of its digits is 165888, while the sum is 44.

The square root of 81384839 is about 9021.3546100350. The cubic root of 81384839 is about 433.3590157691.

The spelling of 81384839 in words is "eighty-one million, three hundred eighty-four thousand, eight hundred thirty-nine".