81100221221021 has 16 divisors (see below), whose sum is σ = 87573428328960. Its totient is φ = 74874376536960.

The previous prime is 81100221221011. The next prime is 81100221221059. The reversal of 81100221221021 is 12012212200118.

It is not a de Polignac number, because 81100221221021 - 2⁶ = 81100221220957 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81100221221011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18094400 + ... + 22127081.

It is an arithmetic number, because the mean of its divisors is an integer number (5473339270560).

Almost surely, 2^{81100221221021} is an apocalyptic number.

It is an amenable number.

81100221221021 is a deficient number, since it is larger than the sum of its proper divisors (6473207107939).

81100221221021 is a wasteful number, since it uses less digits than its factorization.

81100221221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40224556.

The product of its (nonzero) digits is 256, while the sum is 23.

Adding to 81100221221021 its reverse (12012212200118), we get a palindrome (93112433421139).

The spelling of 81100221221021 in words is "eighty-one trillion, one hundred billion, two hundred twenty-one million, two hundred twenty-one thousand, twenty-one".