81994839 has 16 divisors (see below), whose sum is σ = 114476544. Its totient is φ = 52104800.

The previous prime is 81994817. The next prime is 81994867. The reversal of 81994839 is 93849918.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81994839 - 2⁵ = 81994807 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81994791 and 81994800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81994879) 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 15 ways as a sum of consecutive naturals, for example, 19549 + ... + 23369.

It is an arithmetic number, because the mean of its divisors is an integer number (7154784).

Almost surely, 2^81994839 is an apocalyptic number.

81994839 is a deficient number, since it is larger than the sum of its proper divisors (32481705).

81994839 is a wasteful number, since it uses less digits than its factorization.

81994839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4158.

The product of its digits is 559872, while the sum is 51.

The square root of 81994839 is about 9055.1001651003. The cubic root of 81994839 is about 434.4390338048.

The spelling of 81994839 in words is "eighty-one million, nine hundred ninety-four thousand, eight hundred thirty-nine".