21201211181 has 2 divisors, whose sum is σ = 21201211182. Its totient is φ = 21201211180.

The previous prime is 21201211133. The next prime is 21201211183. The reversal of 21201211181 is 18111210212.

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., 20424697225 + 776513956 = 142915^2 + 27866^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201211181 - 2²⁶ = 21134102317 is a prime.

It is a super-2 number, since 2×21201211181² (a number of 21 digits) contains 22 as substring.

Together with 21201211183, 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 (21201211183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600605590 + 10600605591.

It is an arithmetic number, because the mean of its divisors is an integer number (10600605591).

Almost surely, 2^21201211181 is an apocalyptic number.

It is an amenable number.

21201211181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201211181 is an equidigital number, since it uses as much as digits as its factorization.

21201211181 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 21201211181 its reverse (18111210212), we get a palindrome (39312421393).

The spelling of 21201211181 in words is "twenty-one billion, two hundred one million, two hundred eleven thousand, one hundred eighty-one".