21130021181 has 2 divisors, whose sum is σ = 21130021182. Its totient is φ = 21130021180.

The previous prime is 21130021177. The next prime is 21130021183. The reversal of 21130021181 is 18112003112.

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., 21034861156 + 95160025 = 145034^2 + 9755^2 .

It is a cyclic number.

It is not a de Polignac number, because 21130021181 - 2² = 21130021177 is a prime.

It is a super-2 number, since 2×21130021181² (a number of 21 digits) contains 22 as substring.

Together with 21130021183, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21130021183) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565010590 + 10565010591.

It is an arithmetic number, because the mean of its divisors is an integer number (10565010591).

Almost surely, 2^21130021181 is an apocalyptic number.

It is an amenable number.

21130021181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21130021181 is an equidigital number, since it uses as much as digits as its factorization.

21130021181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 20.

Adding to 21130021181 its reverse (18112003112), we get a palindrome (39242024293).

The spelling of 21130021181 in words is "twenty-one billion, one hundred thirty million, twenty-one thousand, one hundred eighty-one".