21120211181 has 2 divisors, whose sum is σ = 21120211182. Its totient is φ = 21120211180.

The previous prime is 21120211093. The next prime is 21120211183. The reversal of 21120211181 is 18111202112.

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., 11522090281 + 9598120900 = 107341^2 + 97970^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21120211181 is a prime.

It is a super-2 number, since 2×21120211181² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

Together with 21120211183, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21120211183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560105590 + 10560105591.

It is an arithmetic number, because the mean of its divisors is an integer number (10560105591).

Almost surely, 2^21120211181 is an apocalyptic number.

It is an amenable number.

21120211181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120211181 is an equidigital number, since it uses as much as digits as its factorization.

21120211181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 20.

Adding to 21120211181 its reverse (18111202112), we get a palindrome (39231413293).

The spelling of 21120211181 in words is "twenty-one billion, one hundred twenty million, two hundred eleven thousand, one hundred eighty-one".