81013221 has 12 divisors (see below), whose sum is σ = 117144300. Its totient is φ = 53951040.

The previous prime is 81013217. The next prime is 81013241. The reversal of 81013221 is 12231018.

It can be written as a sum of positive squares in 2 ways, for example, as 28740321 + 52272900 = 5361^2 + 7230^2 .

It is not a de Polignac number, because 81013221 - 2² = 81013217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81013194 and 81013203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81013241) 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, 5151 + ... + 13731.

It is an arithmetic number, because the mean of its divisors is an integer number (9762025).

Almost surely, 2^81013221 is an apocalyptic number.

It is an amenable number.

81013221 is a deficient number, since it is larger than the sum of its proper divisors (36131079).

81013221 is a wasteful number, since it uses less digits than its factorization.

81013221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9636 (or 9633 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 81013221 is about 9000.7344700308. The cubic root of 81013221 is about 432.6984105295.

Adding to 81013221 its reverse (12231018), we get a palindrome (93244239).

The spelling of 81013221 in words is "eighty-one million, thirteen thousand, two hundred twenty-one".