21220112121181 has 2 divisors, whose sum is σ = 21220112121182. Its totient is φ = 21220112121180.

The previous prime is 21220112121179. The next prime is 21220112121203. The reversal of 21220112121181 is 18112121102212.

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., 20167590015556 + 1052522105625 = 4490834^2 + 1025925^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220112121181 - 2¹ = 21220112121179 is a prime.

It is a super-2 number, since 2×21220112121181² (a number of 27 digits) contains 22 as substring.

Together with 21220112121179, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21220112121281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610056060590 + 10610056060591.

It is an arithmetic number, because the mean of its divisors is an integer number (10610056060591).

Almost surely, 2^{21220112121181} is an apocalyptic number.

It is an amenable number.

21220112121181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220112121181 is an equidigital number, since it uses as much as digits as its factorization.

21220112121181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 256, while the sum is 25.

Adding to 21220112121181 its reverse (18112121102212), we get a palindrome (39332233223393).

The spelling of 21220112121181 in words is "twenty-one trillion, two hundred twenty billion, one hundred twelve million, one hundred twenty-one thousand, one hundred eighty-one".