21021201111221 has 4 divisors (see below), whose sum is σ = 21102995668332. Its totient is φ = 20939406554112.

The previous prime is 21021201111137. The next prime is 21021201111227. The reversal of 21021201111221 is 12211110212012.

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 18013106314225 + 3008094796996 = 4244185^2 + 1734386^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021201111221 - 2²² = 21021196916917 is a prime.

It is a super-2 number, since 2×21021201111221² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21021201111221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021201111227) 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, 40897278170 + ... + 40897278683.

It is an arithmetic number, because the mean of its divisors is an integer number (5275748917083).

Almost surely, 2^{21021201111221} is an apocalyptic number.

It is an amenable number.

21021201111221 is a deficient number, since it is larger than the sum of its proper divisors (81794557111).

21021201111221 is an equidigital number, since it uses as much as digits as its factorization.

21021201111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81794557110.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21021201111221 its reverse (12211110212012), we get a palindrome (33232311323233).

The spelling of 21021201111221 in words is "twenty-one trillion, twenty-one billion, two hundred one million, one hundred eleven thousand, two hundred twenty-one".