21212211222221 has 8 divisors (see below), whose sum is σ = 21343580368704. Its totient is φ = 21080857111200.

The previous prime is 21212211222217. The next prime is 21212211222271. The reversal of 21212211222221 is 12222211221212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21212211222221 - 2² = 21212211222217 is a prime.

It is a super-2 number, since 2×21212211222221² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212211222271) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 921896 + ... + 6578321.

It is an arithmetic number, because the mean of its divisors is an integer number (2667947546088).

Almost surely, 2^{21212211222221} is an apocalyptic number.

It is an amenable number.

21212211222221 is a deficient number, since it is larger than the sum of its proper divisors (131369146483).

21212211222221 is a wasteful number, since it uses less digits than its factorization.

21212211222221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7517731.

The product of its digits is 512, while the sum is 23.

Adding to 21212211222221 its reverse (12222211221212), we get a palindrome (33434422443433).

The spelling of 21212211222221 in words is "twenty-one trillion, two hundred twelve billion, two hundred eleven million, two hundred twenty-two thousand, two hundred twenty-one".