21131331121 has 4 divisors (see below), whose sum is σ = 22050084672. Its totient is φ = 20212577572.

The previous prime is 21131331113. The next prime is 21131331131. The reversal of 21131331121 is 12113313112.

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 a cyclic number.

It is not a de Polignac number, because 21131331121 - 2³ = 21131331113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21131331131) 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, 459376741 + ... + 459376786.

It is an arithmetic number, because the mean of its divisors is an integer number (5512521168).

Almost surely, 2^21131331121 is an apocalyptic number.

It is an amenable number.

21131331121 is a deficient number, since it is larger than the sum of its proper divisors (918753551).

21131331121 is an equidigital number, since it uses as much as digits as its factorization.

21131331121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 918753550.

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

Adding to 21131331121 its reverse (12113313112), we get a palindrome (33244644233).

The spelling of 21131331121 in words is "twenty-one billion, one hundred thirty-one million, three hundred thirty-one thousand, one hundred twenty-one".