21331113121 has 4 divisors (see below), whose sum is σ = 21342150292. Its totient is φ = 21320075952.

The previous prime is 21331113109. The next prime is 21331113131. The reversal of 21331113121 is 12131113312.

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 5470229521 + 15860883600 = 73961^2 + 125940^2 .

It is a cyclic number.

It is not a de Polignac number, because 21331113121 - 2¹⁹ = 21330588833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21331113101) 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, 5515686 + ... + 5519551.

It is an arithmetic number, because the mean of its divisors is an integer number (5335537573).

Almost surely, 2^21331113121 is an apocalyptic number.

It is an amenable number.

21331113121 is a deficient number, since it is larger than the sum of its proper divisors (11037171).

21331113121 is a wasteful number, since it uses less digits than its factorization.

21331113121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11037170.

The product of its digits is 108, while the sum is 19.

Adding to 21331113121 its reverse (12131113312), we get a palindrome (33462226433).

The spelling of 21331113121 in words is "twenty-one billion, three hundred thirty-one million, one hundred thirteen thousand, one hundred twenty-one".