21655212600121 has 2 divisors, whose sum is σ = 21655212600122. Its totient is φ = 21655212600120.

The previous prime is 21655212600059. The next prime is 21655212600127. The reversal of 21655212600121 is 12100621255612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21048239162896 + 606973437225 = 4587836^2 + 779085^2 .

It is a cyclic number.

It is not a de Polignac number, because 21655212600121 - 2¹¹ = 21655212598073 is a prime.

It is not a weakly prime, because it can be changed into another prime (21655212600127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10827606300060 + 10827606300061.

It is an arithmetic number, because the mean of its divisors is an integer number (10827606300061).

Almost surely, 2^{21655212600121} is an apocalyptic number.

It is an amenable number.

21655212600121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21655212600121 is an equidigital number, since it uses as much as digits as its factorization.

21655212600121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14400, while the sum is 34.

Adding to 21655212600121 its reverse (12100621255612), we get a palindrome (33755833855733).

The spelling of 21655212600121 in words is "twenty-one trillion, six hundred fifty-five billion, two hundred twelve million, six hundred thousand, one hundred twenty-one".