81337439 has 4 divisors (see below), whose sum is σ = 81358656. Its totient is φ = 81316224.

The previous prime is 81337411. The next prime is 81337511. The reversal of 81337439 is 93473318.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81337439 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81337409) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3074 + ... + 13119.

It is an arithmetic number, because the mean of its divisors is an integer number (20339664).

Almost surely, 2^81337439 is an apocalyptic number.

81337439 is a deficient number, since it is larger than the sum of its proper divisors (21217).

81337439 is a wasteful number, since it uses less digits than its factorization.

81337439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21216.

The product of its digits is 54432, while the sum is 38.

The square root of 81337439 is about 9018.7271274831. The cubic root of 81337439 is about 433.2748673915.

The spelling of 81337439 in words is "eighty-one million, three hundred thirty-seven thousand, four hundred thirty-nine".