21011112122221 has 16 divisors (see below), whose sum is σ = 22946352589440. Its totient is φ = 19121450523840.

The previous prime is 21011112122201. The next prime is 21011112122261. The reversal of 21011112122221 is 12222121111012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21011112122221 - 2³⁹ = 20461356308333 is a prime.

It is a super-2 number, since 2×21011112122221² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011112122201) 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, 124782075 + ... + 124950343.

It is an arithmetic number, because the mean of its divisors is an integer number (1434147036840).

Almost surely, 2^{21011112122221} is an apocalyptic number.

It is an amenable number.

21011112122221 is a deficient number, since it is larger than the sum of its proper divisors (1935240467219).

21011112122221 is a wasteful number, since it uses less digits than its factorization.

21011112122221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 303636.

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

Adding to 21011112122221 its reverse (12222121111012), we get a palindrome (33233233233233).

The spelling of 21011112122221 in words is "twenty-one trillion, eleven billion, one hundred twelve million, one hundred twenty-two thousand, two hundred twenty-one".