81100221221001 has 16 divisors (see below), whose sum is σ = 109155098032128. Its totient is φ = 53557407590400.

The previous prime is 81100221220957. The next prime is 81100221221003. The reversal of 81100221221001 is 10012212200118.

It is not a de Polignac number, because 81100221221001 - 2¹¹ = 81100221218953 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81100221221003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 165794370 + ... + 166282811.

It is an arithmetic number, because the mean of its divisors is an integer number (6822193627008).

Almost surely, 2^{81100221221001} is an apocalyptic number.

It is an amenable number.

81100221221001 is a deficient number, since it is larger than the sum of its proper divisors (28054876811127).

81100221221001 is a wasteful number, since it uses less digits than its factorization.

81100221221001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 332077952.

The product of its (nonzero) digits is 128, while the sum is 21.

Adding to 81100221221001 its reverse (10012212200118), we get a palindrome (91112433421119).

The spelling of 81100221221001 in words is "eighty-one trillion, one hundred billion, two hundred twenty-one million, two hundred twenty-one thousand, one".