21110211212221 has 4 divisors (see below), whose sum is σ = 21111036403392. Its totient is φ = 21109386021052.

The previous prime is 21110211212213. The next prime is 21110211212257. The reversal of 21110211212221 is 12221211201112.

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 21110211212221 - 2³ = 21110211212213 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 (21110211212521) 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, 412557211 + ... + 412608376.

It is an arithmetic number, because the mean of its divisors is an integer number (5277759100848).

Almost surely, 2^{21110211212221} is an apocalyptic number.

It is an amenable number.

21110211212221 is a deficient number, since it is larger than the sum of its proper divisors (825191171).

21110211212221 is an equidigital number, since it uses as much as digits as its factorization.

21110211212221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 825191170.

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

Adding to 21110211212221 its reverse (12221211201112), we get a palindrome (33331422413333).

The spelling of 21110211212221 in words is "twenty-one trillion, one hundred ten billion, two hundred eleven million, two hundred twelve thousand, two hundred twenty-one".