21121200000021 has 48 divisors (see below), whose sum is σ = 33472686143232. Its totient is φ = 11791408189440.

The previous prime is 21121200000013. The next prime is 21121200000083. The reversal of 21121200000021 is 12000000212112.

It is not a de Polignac number, because 21121200000021 - 2³ = 21121200000013 is a prime.

It is a super-2 number, since 2×21121200000021² (a number of 27 digits) contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21121199999952 and 21121200000006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121200000421) 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, 36121180 + ... + 36701253.

It is an arithmetic number, because the mean of its divisors is an integer number (697347627984).

Almost surely, 2^{21121200000021} is an apocalyptic number.

It is an amenable number.

21121200000021 is a deficient number, since it is larger than the sum of its proper divisors (12351486143211).

21121200000021 is a wasteful number, since it uses less digits than its factorization.

21121200000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72822522 (or 72822511 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21121200000021 its reverse (12000000212112), we get a palindrome (33121200212133).

It can be divided in two parts, 2112 and 1200000021, that multiplied together give a palindrome (2534400044352).

The spelling of 21121200000021 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred million, twenty-one", and thus it is an aban number.