21321121122181 has 2 divisors, whose sum is σ = 21321121122182. Its totient is φ = 21321121122180.

The previous prime is 21321121122143. The next prime is 21321121122239. The reversal of 21321121122181 is 18122112112312.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13742849908225 + 7578271213956 = 3707135^2 + 2752866^2 .

It is a cyclic number.

It is not a de Polignac number, because 21321121122181 - 2¹⁵ = 21321121089413 is a prime.

It is a super-2 number, since 2×21321121122181² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21321121122101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660560561090 + 10660560561091.

It is an arithmetic number, because the mean of its divisors is an integer number (10660560561091).

Almost surely, 2^{21321121122181} is an apocalyptic number.

It is an amenable number.

21321121122181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21321121122181 is an equidigital number, since it uses as much as digits as its factorization.

21321121122181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 768, while the sum is 28.

Adding to 21321121122181 its reverse (18122112112312), we get a palindrome (39443233234493).

The spelling of 21321121122181 in words is "twenty-one trillion, three hundred twenty-one billion, one hundred twenty-one million, one hundred twenty-two thousand, one hundred eighty-one".