81128031 has 4 divisors (see below), whose sum is σ = 108170712. Its totient is φ = 54085352.

The previous prime is 81128027. The next prime is 81128077. The reversal of 81128031 is 13082118.

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

It is a cyclic number.

It is not a de Polignac number, because 81128031 - 2² = 81128027 is a prime.

It is a super-2 number, since 2×81128031² = 13163514827873922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81127992 and 81128010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81108031) 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 3 ways as a sum of consecutive naturals, for example, 13521336 + ... + 13521341.

It is an arithmetic number, because the mean of its divisors is an integer number (27042678).

Almost surely, 2^81128031 is an apocalyptic number.

81128031 is a deficient number, since it is larger than the sum of its proper divisors (27042681).

81128031 is a wasteful number, since it uses less digits than its factorization.

81128031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27042680.

The product of its (nonzero) digits is 384, while the sum is 24.

The square root of 81128031 is about 9007.1100248637. The cubic root of 81128031 is about 432.9027173279.

The spelling of 81128031 in words is "eighty-one million, one hundred twenty-eight thousand, thirty-one".