21212112212101 has 4 divisors (see below), whose sum is σ = 21218697782604. Its totient is φ = 21205526641600.

The previous prime is 21212112212087. The next prime is 21212112212189. The reversal of 21212112212101 is 10121221121212.

It is a happy number.

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 11604753230625 + 9607358981476 = 3406575^2 + 3099574^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212112212101 - 2⁷ = 21212112211973 is a prime.

It is a super-2 number, since 2×21212112212101² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212112212191) 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, 3292780420 + ... + 3292786861.

It is an arithmetic number, because the mean of its divisors is an integer number (5304674445651).

Almost surely, 2^{21212112212101} is an apocalyptic number.

It is an amenable number.

21212112212101 is a deficient number, since it is larger than the sum of its proper divisors (6585570503).

21212112212101 is an equidigital number, since it uses as much as digits as its factorization.

21212112212101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6585570502.

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

Adding to 21212112212101 its reverse (10121221121212), we get a palindrome (31333333333313).

The spelling of 21212112212101 in words is "twenty-one trillion, two hundred twelve billion, one hundred twelve million, two hundred twelve thousand, one hundred one".