21031113121 has 4 divisors (see below), whose sum is σ = 21031403200. Its totient is φ = 21030823044.

The previous prime is 21031113109. The next prime is 21031113149. The reversal of 21031113121 is 12131113012.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21031113121 - 2²⁵ = 20997558689 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21031113095 and 21031113104.

It is not an unprimeable number, because it can be changed into a prime (21031116121) 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, 69100 + ... + 216418.

It is an arithmetic number, because the mean of its divisors is an integer number (5257850800).

Almost surely, 2^21031113121 is an apocalyptic number.

It is an amenable number.

21031113121 is a deficient number, since it is larger than the sum of its proper divisors (290079).

21031113121 is a wasteful number, since it uses less digits than its factorization.

21031113121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290078.

The product of its (nonzero) digits is 36, while the sum is 16.

Adding to 21031113121 its reverse (12131113012), we get a palindrome (33162226133).

The spelling of 21031113121 in words is "twenty-one billion, thirty-one million, one hundred thirteen thousand, one hundred twenty-one".