81989439 has 32 divisors (see below), whose sum is σ = 128440320. Its totient is φ = 45556992.

The previous prime is 81989407. The next prime is 81989443. The reversal of 81989439 is 93498918.

It is a happy number.

It is not a de Polignac number, because 81989439 - 2⁵ = 81989407 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81989391 and 81989400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81989459) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 120769 + ... + 121445.

It is an arithmetic number, because the mean of its divisors is an integer number (4013760).

Almost surely, 2^81989439 is an apocalyptic number.

81989439 is a deficient number, since it is larger than the sum of its proper divisors (46450881).

81989439 is a wasteful number, since it uses less digits than its factorization.

81989439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 839.

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

The square root of 81989439 is about 9054.8019856869. The cubic root of 81989439 is about 434.4294965285.

It can be divided in two parts, 81989 and 439, that added together give a palindrome (82428).

The spelling of 81989439 in words is "eighty-one million, nine hundred eighty-nine thousand, four hundred thirty-nine".