81839447 has 4 divisors (see below), whose sum is σ = 82428360. Its totient is φ = 81250536.

The previous prime is 81839437. The next prime is 81839467. The reversal of 81839447 is 74493818.

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 81839447 - 2⁶ = 81839383 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81839398 and 81839407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81839437) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 294248 + ... + 294525.

It is an arithmetic number, because the mean of its divisors is an integer number (20607090).

Almost surely, 2^81839447 is an apocalyptic number.

81839447 is a deficient number, since it is larger than the sum of its proper divisors (588913).

81839447 is a wasteful number, since it uses less digits than its factorization.

81839447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 588912.

The product of its digits is 193536, while the sum is 44.

The square root of 81839447 is about 9046.5157381171. The cubic root of 81839447 is about 434.1644187919.

The spelling of 81839447 in words is "eighty-one million, eight hundred thirty-nine thousand, four hundred forty-seven".