81394439 has 6 divisors (see below), whose sum is σ = 94683384. Its totient is φ = 69766620.

The previous prime is 81394421. The next prime is 81394441. The reversal of 81394439 is 93449318.

It is a de Polignac number, because none of the positive numbers 2^k-81394439 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81394396 and 81394405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81394409) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 830507 + ... + 830604.

It is an arithmetic number, because the mean of its divisors is an integer number (15780564).

Almost surely, 2^81394439 is an apocalyptic number.

81394439 is a deficient number, since it is larger than the sum of its proper divisors (13288945).

81394439 is a wasteful number, since it uses less digits than its factorization.

81394439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1661125 (or 1661118 counting only the distinct ones).

The product of its digits is 93312, while the sum is 41.

The square root of 81394439 is about 9021.8866652159. The cubic root of 81394439 is about 433.3760544995.

The spelling of 81394439 in words is "eighty-one million, three hundred ninety-four thousand, four hundred thirty-nine".