81157439 has 16 divisors (see below), whose sum is σ = 94693536. Its totient is φ = 68736000.

The previous prime is 81157429. The next prime is 81157441. The reversal of 81157439 is 93475118.

It is a cyclic number.

It is not a de Polignac number, because 81157439 - 2²⁰ = 80108863 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81157429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16739 + ... + 21035.

It is an arithmetic number, because the mean of its divisors is an integer number (5918346).

Almost surely, 2^81157439 is an apocalyptic number.

81157439 is a deficient number, since it is larger than the sum of its proper divisors (13536097).

81157439 is a wasteful number, since it uses less digits than its factorization.

81157439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4426.

The product of its digits is 30240, while the sum is 38.

The square root of 81157439 is about 9008.7423650585. The cubic root of 81157439 is about 432.9550184665.

The spelling of 81157439 in words is "eighty-one million, one hundred fifty-seven thousand, four hundred thirty-nine".