81519831 has 8 divisors (see below), whose sum is σ = 120770160. Its totient is φ = 54346536.

The previous prime is 81519799. The next prime is 81519839. The reversal of 81519831 is 13891518.

It is not a de Polignac number, because 81519831 - 2⁵ = 81519799 is a prime.

It is a super-2 number, since 2×81519831² = 13290965692537122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81519839) 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 7 ways as a sum of consecutive naturals, for example, 1509600 + ... + 1509653.

It is an arithmetic number, because the mean of its divisors is an integer number (15096270).

Almost surely, 2^81519831 is an apocalyptic number.

81519831 is a deficient number, since it is larger than the sum of its proper divisors (39250329).

81519831 is a wasteful number, since it uses less digits than its factorization.

81519831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3019262 (or 3019256 counting only the distinct ones).

The product of its digits is 8640, while the sum is 36.

The square root of 81519831 is about 9028.8333133357. The cubic root of 81519831 is about 433.5984857832.

The spelling of 81519831 in words is "eighty-one million, five hundred nineteen thousand, eight hundred thirty-one".