21131424121 has 4 divisors (see below), whose sum is σ = 21340646244. Its totient is φ = 20922202000.

The previous prime is 21131424107. The next prime is 21131424163. The reversal of 21131424121 is 12142413112.

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 20264946025 + 866478096 = 142355^2 + 29436^2 .

It is a cyclic number.

It is not a de Polignac number, because 21131424121 - 2²¹ = 21129326969 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21131424092 and 21131424101.

It is not an unprimeable number, because it can be changed into a prime (21131424221) 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, 104610910 + ... + 104611111.

It is an arithmetic number, because the mean of its divisors is an integer number (5335161561).

Almost surely, 2^21131424121 is an apocalyptic number.

It is an amenable number.

21131424121 is a deficient number, since it is larger than the sum of its proper divisors (209222123).

21131424121 is a wasteful number, since it uses less digits than its factorization.

21131424121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209222122.

The product of its digits is 384, while the sum is 22.

Adding to 21131424121 its reverse (12142413112), we get a palindrome (33273837233).

The spelling of 21131424121 in words is "twenty-one billion, one hundred thirty-one million, four hundred twenty-four thousand, one hundred twenty-one".