81005031 has 12 divisors (see below), whose sum is σ = 117290680. Its totient is φ = 53872560.

The previous prime is 81005009. The next prime is 81005039. The reversal of 81005031 is 13050018.

It is a happy number.

It is not a de Polignac number, because 81005031 - 2¹¹ = 81002983 is a prime.

It is a super-2 number, since 2×81005031² = 13123630094621922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81004995 and 81005013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81005039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6901 + ... + 14478.

Almost surely, 2^81005031 is an apocalyptic number.

81005031 is a deficient number, since it is larger than the sum of its proper divisors (36285649).

81005031 is a wasteful number, since it uses less digits than its factorization.

81005031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21806 (or 21803 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 81005031 is about 9000.2794956601. The cubic root of 81005031 is about 432.6838288791.

Adding to 81005031 its reverse (13050018), we get a palindrome (94055049).

It can be divided in two parts, 8100 and 5031, that added together give a palindrome (13131).

The spelling of 81005031 in words is "eighty-one million, five thousand, thirty-one".