21111222221 has 8 divisors (see below), whose sum is σ = 23188528320. Its totient is φ = 19130535072.

The previous prime is 21111222199. The next prime is 21111222287. The reversal of 21111222221 is 12222211112.

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 21111222221 - 2⁶ = 21111222157 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21111222221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111222521) 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, 24154280 + ... + 24155153.

It is an arithmetic number, because the mean of its divisors is an integer number (2898566040).

Almost surely, 2^21111222221 is an apocalyptic number.

It is an amenable number.

21111222221 is a deficient number, since it is larger than the sum of its proper divisors (2077306099).

21111222221 is a wasteful number, since it uses less digits than its factorization.

21111222221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48309475.

The product of its digits is 64, while the sum is 17.

Adding to 21111222221 its reverse (12222211112), we get a palindrome (33333433333).

The spelling of 21111222221 in words is "twenty-one billion, one hundred eleven million, two hundred twenty-two thousand, two hundred twenty-one".