21213122131181 has 2 divisors, whose sum is σ = 21213122131182. Its totient is φ = 21213122131180.

The previous prime is 21213122131153. The next prime is 21213122131219. The reversal of 21213122131181 is 18113122131212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16237394089225 + 4975728041956 = 4029565^2 + 2230634^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213122131181 - 2¹⁴ = 21213122114797 is a prime.

It is a super-2 number, since 2×21213122131181² (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 (21213122131141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606561065590 + 10606561065591.

It is an arithmetic number, because the mean of its divisors is an integer number (10606561065591).

Almost surely, 2^{21213122131181} is an apocalyptic number.

It is an amenable number.

21213122131181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213122131181 is an equidigital number, since it uses as much as digits as its factorization.

21213122131181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 29.

Adding to 21213122131181 its reverse (18113122131212), we get a palindrome (39326244262393).

The spelling of 21213122131181 in words is "twenty-one trillion, two hundred thirteen billion, one hundred twenty-two million, one hundred thirty-one thousand, one hundred eighty-one".