21112131121 has 2 divisors, whose sum is σ = 21112131122. Its totient is φ = 21112131120.

The previous prime is 21112131083. The next prime is 21112131133. The reversal of 21112131121 is 12113121112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13216031521 + 7896099600 = 114961^2 + 88860^2 .

It is a cyclic number.

It is not a de Polignac number, because 21112131121 - 2¹⁹ = 21111606833 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21112131095 and 21112131104.

It is not a weakly prime, because it can be changed into another prime (21112131721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10556065560 + 10556065561.

It is an arithmetic number, because the mean of its divisors is an integer number (10556065561).

Almost surely, 2^21112131121 is an apocalyptic number.

It is an amenable number.

21112131121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21112131121 is an equidigital number, since it uses as much as digits as its factorization.

21112131121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24, while the sum is 16.

Adding to 21112131121 its reverse (12113121112), we get a palindrome (33225252233).

It can be divided in two parts, 211121 and 31121, that added together give a palindrome (242242).

The spelling of 21112131121 in words is "twenty-one billion, one hundred twelve million, one hundred thirty-one thousand, one hundred twenty-one".