81109439 has 16 divisors (see below), whose sum is σ = 86209536. Its totient is φ = 76204800.

The previous prime is 81109429. The next prime is 81109447. The reversal of 81109439 is 93490118.

It is a cyclic number.

It is not a de Polignac number, because 81109439 - 2²⁰ = 80060863 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81109399 and 81109408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81109409) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 192449 + ... + 192869.

It is an arithmetic number, because the mean of its divisors is an integer number (5388096).

Almost surely, 2^81109439 is an apocalyptic number.

81109439 is a deficient number, since it is larger than the sum of its proper divisors (5100097).

81109439 is a wasteful number, since it uses less digits than its factorization.

81109439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 626.

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 81109439 is about 9006.0778921793. The cubic root of 81109439 is about 432.8696455601.

The spelling of 81109439 in words is "eighty-one million, one hundred nine thousand, four hundred thirty-nine".