21211110122221 has 16 divisors (see below), whose sum is σ = 23371740720000. Its totient is φ = 19160417377728.

The previous prime is 21211110122117. The next prime is 21211110122317. The reversal of 21211110122221 is 12222101111212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21211110122221 - 2¹⁹ = 21211109597933 is a prime.

It is a super-2 number, since 2×21211110122221² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211110125221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 76419846 + ... + 76696903.

It is an arithmetic number, because the mean of its divisors is an integer number (1460733795000).

Almost surely, 2^{21211110122221} is an apocalyptic number.

It is an amenable number.

21211110122221 is a deficient number, since it is larger than the sum of its proper divisors (2160630597779).

21211110122221 is a wasteful number, since it uses less digits than its factorization.

21211110122221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153117108.

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 21211110122221 its reverse (12222101111212), we get a palindrome (33433211233433).

The spelling of 21211110122221 in words is "twenty-one trillion, two hundred eleven billion, one hundred ten million, one hundred twenty-two thousand, two hundred twenty-one".