21101112212221 has 4 divisors (see below), whose sum is σ = 21101519393500. Its totient is φ = 21100705030944.

The previous prime is 21101112212113. The next prime is 21101112212233. The reversal of 21101112212221 is 12221221110112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10999769228100 + 10101342984121 = 3316590^2 + 3178261^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21101112212221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101112212261) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 203512896 + ... + 203616553.

It is an arithmetic number, because the mean of its divisors is an integer number (5275379848375).

Almost surely, 2^{21101112212221} is an apocalyptic number.

It is an amenable number.

21101112212221 is a deficient number, since it is larger than the sum of its proper divisors (407181279).

21101112212221 is an equidigital number, since it uses as much as digits as its factorization.

21101112212221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407181278.

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 21101112212221 its reverse (12221221110112), we get a palindrome (33322333322333).

The spelling of 21101112212221 in words is "twenty-one trillion, one hundred one billion, one hundred twelve million, two hundred twelve thousand, two hundred twenty-one".