21222212221 has 16 divisors (see below), whose sum is σ = 25294474240. Its totient is φ = 17422179840.

The previous prime is 21222212201. The next prime is 21222212237. The reversal of 21222212221 is 12221222212.

It is a cyclic number.

It is not a de Polignac number, because 21222212221 - 2²⁹ = 20685341309 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21222212201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 483066 + ... + 525163.

It is an arithmetic number, because the mean of its divisors is an integer number (1580904640).

Almost surely, 2^21222212221 is an apocalyptic number.

It is an amenable number.

21222212221 is a deficient number, since it is larger than the sum of its proper divisors (4072262019).

21222212221 is a wasteful number, since it uses less digits than its factorization.

21222212221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1008364.

The product of its digits is 256, while the sum is 19.

Adding to 21222212221 its reverse (12221222212), we get a palindrome (33443434433).

Subtracting from 21222212221 its reverse (12221222212), we obtain a palindrome (9000990009).

The spelling of 21222212221 in words is "twenty-one billion, two hundred twenty-two million, two hundred twelve thousand, two hundred twenty-one".