21121202121111 has 96 divisors (see below), whose sum is σ = 34062382448640. Its totient is φ = 12551071564800.

The previous prime is 21121202121073. The next prime is 21121202121241. The reversal of 21121202121111 is 11112120212112.

It is a happy number.

21121202121111 is a `hidden beast` number, since 211 + 21 + 202 + 121 + 111 = 666.

It is not a de Polignac number, because 21121202121111 - 2²⁵ = 21121168566679 is a prime.

It is a super-2 number, since 2×21121202121111² (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 (21121202111111) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 62234421 + ... + 62572881.

It is an arithmetic number, because the mean of its divisors is an integer number (354816483840).

Almost surely, 2^{21121202121111} is an apocalyptic number.

21121202121111 is a deficient number, since it is larger than the sum of its proper divisors (12941180327529).

21121202121111 is a wasteful number, since it uses less digits than its factorization.

21121202121111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 338797 (or 338794 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 18.

Adding to 21121202121111 its reverse (11112120212112), we get a palindrome (32233322333223).

It can be divided in two parts, 2112120212111 and 1, that added together give a palindrome (2112120212112).

The spelling of 21121202121111 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred two million, one hundred twenty-one thousand, one hundred eleven".