21432412121 has 4 divisors (see below), whose sum is σ = 21460139172. Its totient is φ = 21404685072.

The previous prime is 21432412109. The next prime is 21432412181. The reversal of 21432412121 is 12121423412.

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 5972971225 + 15459440896 = 77285^2 + 124336^2 .

It is a cyclic number.

It is not a de Polignac number, because 21432412121 - 2²⁶ = 21365303257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21432412181) 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, 13862366 + ... + 13863911.

It is an arithmetic number, because the mean of its divisors is an integer number (5365034793).

Almost surely, 2^21432412121 is an apocalyptic number.

It is an amenable number.

21432412121 is a deficient number, since it is larger than the sum of its proper divisors (27727051).

21432412121 is an equidigital number, since it uses as much as digits as its factorization.

21432412121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27727050.

The product of its digits is 768, while the sum is 23.

Adding to 21432412121 its reverse (12121423412), we get a palindrome (33553835533).

The spelling of 21432412121 in words is "twenty-one billion, four hundred thirty-two million, four hundred twelve thousand, one hundred twenty-one".