21022122221 has 16 divisors (see below), whose sum is σ = 21474361920. Its totient is φ = 20574933120.

The previous prime is 21022122211. The next prime is 21022122257. The reversal of 21022122221 is 12222122012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21022122221 - 2²⁶ = 20955013357 is a prime.

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 21022122221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21022122211) 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, 5743490 + ... + 5747148.

It is an arithmetic number, because the mean of its divisors is an integer number (1342147620).

Almost surely, 2^21022122221 is an apocalyptic number.

It is an amenable number.

21022122221 is a deficient number, since it is larger than the sum of its proper divisors (452239699).

21022122221 is a wasteful number, since it uses less digits than its factorization.

21022122221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4316.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21022122221 its reverse (12222122012), we get a palindrome (33244244233).

The spelling of 21022122221 in words is "twenty-one billion, twenty-two million, one hundred twenty-two thousand, two hundred twenty-one".