81831513 has 8 divisors (see below), whose sum is σ = 110189376. Its totient is φ = 54014000.

The previous prime is 81831511. The next prime is 81831517. The reversal of 81831513 is 31513818.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81831513 - 2¹ = 81831511 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81831511) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 134733 + ... + 135338.

It is an arithmetic number, because the mean of its divisors is an integer number (13773672).

Almost surely, 2^81831513 is an apocalyptic number.

It is an amenable number.

81831513 is a deficient number, since it is larger than the sum of its proper divisors (28357863).

81831513 is a wasteful number, since it uses less digits than its factorization.

81831513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270175.

The product of its digits is 2880, while the sum is 30.

The square root of 81831513 is about 9046.0772161197. The cubic root of 81831513 is about 434.1503881830.

The spelling of 81831513 in words is "eighty-one million, eight hundred thirty-one thousand, five hundred thirteen".