21111211202121 has 48 divisors (see below), whose sum is σ = 33525210014400. Its totient is φ = 12753152313984.

The previous prime is 21111211202119. The next prime is 21111211202131. The reversal of 21111211202121 is 12120211211112.

It is a happy number.

21111211202121 is a `hidden beast` number, since 21 + 111 + 211 + 202 + 121 = 666.

It is not a de Polignac number, because 21111211202121 - 2¹ = 21111211202119 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21111211202094 and 21111211202103.

It is not an unprimeable number, because it can be changed into a prime (21111211202131) 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 47 ways as a sum of consecutive naturals, for example, 27903706 + ... + 28650291.

It is an arithmetic number, because the mean of its divisors is an integer number (698441875300).

Almost surely, 2^{21111211202121} is an apocalyptic number.

It is an amenable number.

21111211202121 is a deficient number, since it is larger than the sum of its proper divisors (12413998812279).

21111211202121 is a wasteful number, since it uses less digits than its factorization.

21111211202121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56554118 (or 56554115 counting only the distinct ones).

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

Adding to 21111211202121 its reverse (12120211211112), we get a palindrome (33231422413233).

The spelling of 21111211202121 in words is "twenty-one trillion, one hundred eleven billion, two hundred eleven million, two hundred two thousand, one hundred twenty-one".