21111100102121 has 4 divisors (see below), whose sum is σ = 21111112271700. Its totient is φ = 21111087932544.

The previous prime is 21111100102067. The next prime is 21111100102177. The reversal of 21111100102121 is 12120100111112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12586452012121 + 8524648090000 = 3547739^2 + 2919700^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111100102121 - 2³⁸ = 20836222195177 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21111100102096 and 21111100102105.

It is not an unprimeable number, because it can be changed into a prime (21111100102321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2941376 + ... + 7132593.

It is an arithmetic number, because the mean of its divisors is an integer number (5277778067925).

Almost surely, 2^{21111100102121} is an apocalyptic number.

It is an amenable number.

21111100102121 is a deficient number, since it is larger than the sum of its proper divisors (12169579).

21111100102121 is a wasteful number, since it uses less digits than its factorization.

21111100102121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12169578.

The product of its (nonzero) digits is 8, while the sum is 14.

Adding to 21111100102121 its reverse (12120100111112), we get a palindrome (33231200213233).

The spelling of 21111100102121 in words is "twenty-one trillion, one hundred eleven billion, one hundred million, one hundred two thousand, one hundred twenty-one".