21222021221221 has 4 divisors (see below), whose sum is σ = 21222240492672. Its totient is φ = 21221801949772.

The previous prime is 21222021221153. The next prime is 21222021221263. The reversal of 21222021221221 is 12212212022212.

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 21222021221221 - 2⁹ = 21222021220709 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21222021221192 and 21222021221201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21222021221521) 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, 109490485 + ... + 109684138.

It is an arithmetic number, because the mean of its divisors is an integer number (5305560123168).

Almost surely, 2^{21222021221221} is an apocalyptic number.

It is an amenable number.

21222021221221 is a deficient number, since it is larger than the sum of its proper divisors (219271451).

21222021221221 is an equidigital number, since it uses as much as digits as its factorization.

21222021221221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219271450.

The product of its (nonzero) digits is 512, while the sum is 22.

Adding to 21222021221221 its reverse (12212212022212), we get a palindrome (33434233243433).

The spelling of 21222021221221 in words is "twenty-one trillion, two hundred twenty-two billion, twenty-one million, two hundred twenty-one thousand, two hundred twenty-one".