21001112201221 has 2 divisors, whose sum is σ = 21001112201222. Its totient is φ = 21001112201220.

The previous prime is 21001112201177. The next prime is 21001112201227. The reversal of 21001112201221 is 12210221110012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12448470441121 + 8552641760100 = 3528239^2 + 2924490^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001112201221 - 2²⁵ = 21001078646789 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21001112201195 and 21001112201204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001112201227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500556100610 + 10500556100611.

It is an arithmetic number, because the mean of its divisors is an integer number (10500556100611).

Almost surely, 2^{21001112201221} is an apocalyptic number.

It is an amenable number.

21001112201221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001112201221 is an equidigital number, since it uses as much as digits as its factorization.

21001112201221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21001112201221 its reverse (12210221110012), we get a palindrome (33211333311233).

The spelling of 21001112201221 in words is "twenty-one trillion, one billion, one hundred twelve million, two hundred one thousand, two hundred twenty-one".