21231121121 has 4 divisors (see below), whose sum is σ = 24264138432. Its totient is φ = 18198103812.

The previous prime is 21231121117. The next prime is 21231121127. The reversal of 21231121121 is 12112113212.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21231121121 - 2² = 21231121117 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21231121121.

It is not an unprimeable number, because it can be changed into a prime (21231121127) 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, 1516508645 + ... + 1516508658.

It is an arithmetic number, because the mean of its divisors is an integer number (6066034608).

Almost surely, 2^21231121121 is an apocalyptic number.

It is an amenable number.

21231121121 is a deficient number, since it is larger than the sum of its proper divisors (3033017311).

21231121121 is an equidigital number, since it uses as much as digits as its factorization.

21231121121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3033017310.

The product of its digits is 48, while the sum is 17.

Adding to 21231121121 its reverse (12112113212), we get a palindrome (33343234333).

The spelling of 21231121121 in words is "twenty-one billion, two hundred thirty-one million, one hundred twenty-one thousand, one hundred twenty-one".