21221111122221 has 8 divisors (see below), whose sum is σ = 28419461591904. Its totient is φ = 14085084033680.

The previous prime is 21221111122147. The next prime is 21221111122223. The reversal of 21221111122221 is 12222111112212.

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 21221111122221 - 2¹⁷ = 21221110991149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221111122223) 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, 15580844490 + ... + 15580845851.

It is an arithmetic number, because the mean of its divisors is an integer number (3552432698988).

Almost surely, 2^{21221111122221} is an apocalyptic number.

It is an amenable number.

21221111122221 is a deficient number, since it is larger than the sum of its proper divisors (7198350469683).

21221111122221 is a wasteful number, since it uses less digits than its factorization.

21221111122221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31161690571.

The product of its digits is 128, while the sum is 21.

Adding to 21221111122221 its reverse (12222111112212), we get a palindrome (33443222234433).

The spelling of 21221111122221 in words is "twenty-one trillion, two hundred twenty-one billion, one hundred eleven million, one hundred twenty-two thousand, two hundred twenty-one".