21101011212121 has 4 divisors (see below), whose sum is σ = 21137581422772. Its totient is φ = 21064441001472.

The previous prime is 21101011212079. The next prime is 21101011212131. The reversal of 21101011212121 is 12121211010112.

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 20344032910096 + 756978302025 = 4510436^2 + 870045^2 .

It is a cyclic number.

It is not a de Polignac number, because 21101011212121 - 2²³ = 21101002823513 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21101011212095 and 21101011212104.

It is not an unprimeable number, because it can be changed into a prime (21101011212131) 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 3 ways as a sum of consecutive naturals, for example, 18285104460 + ... + 18285105613.

It is an arithmetic number, because the mean of its divisors is an integer number (5284395355693).

Almost surely, 2^{21101011212121} is an apocalyptic number.

It is an amenable number.

21101011212121 is a deficient number, since it is larger than the sum of its proper divisors (36570210651).

21101011212121 is an equidigital number, since it uses as much as digits as its factorization.

21101011212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36570210650.

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

Adding to 21101011212121 its reverse (12121211010112), we get a palindrome (33222222222233).

It can be divided in two parts, 211010112 and 12121, that multiplied together give a palindrome (2557653567552).

The spelling of 21101011212121 in words is "twenty-one trillion, one hundred one billion, eleven million, two hundred twelve thousand, one hundred twenty-one".