21131231124121 has 2 divisors, whose sum is σ = 21131231124122. Its totient is φ = 21131231124120.

The previous prime is 21131231124079. The next prime is 21131231124137. The reversal of 21131231124121 is 12142113213112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19465038086400 + 1666193037721 = 4411920^2 + 1290811^2 .

It is a cyclic number.

It is not a de Polignac number, because 21131231124121 - 2²⁵ = 21131197569689 is a prime.

It is a super-2 number, since 2×21131231124121² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21131231124151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565615562060 + 10565615562061.

It is an arithmetic number, because the mean of its divisors is an integer number (10565615562061).

Almost surely, 2^{21131231124121} is an apocalyptic number.

It is an amenable number.

21131231124121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21131231124121 is an equidigital number, since it uses as much as digits as its factorization.

21131231124121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 576, while the sum is 25.

Adding to 21131231124121 its reverse (12142113213112), we get a palindrome (33273344337233).

The spelling of 21131231124121 in words is "twenty-one trillion, one hundred thirty-one billion, two hundred thirty-one million, one hundred twenty-four thousand, one hundred twenty-one".