81005331 has 16 divisors (see below), whose sum is σ = 117992448. Its totient is φ = 49024800.

The previous prime is 81005329. The next prime is 81005363. The reversal of 81005331 is 13350018.

It is a happy number.

It is not a de Polignac number, because 81005331 - 2¹ = 81005329 is a prime.

It is a super-2 number, since 2×81005331² = 13123727300839122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81005298 and 81005307.

It is not an unprimeable number, because it can be changed into a prime (81005311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31465 + ... + 33941.

It is an arithmetic number, because the mean of its divisors is an integer number (7374528).

Almost surely, 2^81005331 is an apocalyptic number.

81005331 is a deficient number, since it is larger than the sum of its proper divisors (36987117).

81005331 is a wasteful number, since it uses less digits than its factorization.

81005331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3482.

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 81005331 is about 9000.2961617938. The cubic root of 81005331 is about 432.6843630228.

Adding to 81005331 its reverse (13350018), we get a palindrome (94355349).

It can be divided in two parts, 8100 and 5331, that added together give a palindrome (13431).

The spelling of 81005331 in words is "eighty-one million, five thousand, three hundred thirty-one".