81258104101221 has 24 divisors (see below), whose sum is σ = 117986560716024. Its totient is φ = 53888886737280.

The previous prime is 81258104101219. The next prime is 81258104101241. The reversal of 81258104101221 is 12210140185218.

81258104101221 is a `hidden beast` number, since 8 + 1 + 2 + 5 + 8 + 10 + 410 + 1 + 221 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 41800685969025 + 39457418132196 = 6465345^2 + 6281514^2 .

It is not a de Polignac number, because 81258104101221 - 2¹ = 81258104101219 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81258104101241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8186055 + ... + 15150171.

It is an arithmetic number, because the mean of its divisors is an integer number (4916106696501).

Almost surely, 2^{81258104101221} is an apocalyptic number.

It is an amenable number.

81258104101221 is a deficient number, since it is larger than the sum of its proper divisors (36728456614803).

81258104101221 is a wasteful number, since it uses less digits than its factorization.

81258104101221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6970901 (or 6970898 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 36.

Adding to 81258104101221 its reverse (12210140185218), we get a palindrome (93468244286439).

The spelling of 81258104101221 in words is "eighty-one trillion, two hundred fifty-eight billion, one hundred four million, one hundred one thousand, two hundred twenty-one".