21221100111021 has 4 divisors (see below), whose sum is σ = 28294800148032. Its totient is φ = 14147400074012.

The previous prime is 21221100111019. The next prime is 21221100111077. The reversal of 21221100111021 is 12011100112212.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21221100111021 - 2¹ = 21221100111019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221100111091) 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, 3536850018501 + ... + 3536850018506.

It is an arithmetic number, because the mean of its divisors is an integer number (7073700037008).

Almost surely, 2^{21221100111021} is an apocalyptic number.

It is an amenable number.

21221100111021 is a deficient number, since it is larger than the sum of its proper divisors (7073700037011).

21221100111021 is an equidigital number, since it uses as much as digits as its factorization.

21221100111021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7073700037010.

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 21221100111021 its reverse (12011100112212), we get a palindrome (33232200223233).

The spelling of 21221100111021 in words is "twenty-one trillion, two hundred twenty-one billion, one hundred million, one hundred eleven thousand, twenty-one".