21123213211211 has 2 divisors, whose sum is σ = 21123213211212. Its totient is φ = 21123213211210.

The previous prime is 21123213211123. The next prime is 21123213211229. The reversal of 21123213211211 is 11211231232112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21123213211211 - 2¹⁸ = 21123212949067 is a prime.

It is not a weakly prime, because it can be changed into another prime (21123213211271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561606605605 + 10561606605606.

It is an arithmetic number, because the mean of its divisors is an integer number (10561606605606).

Almost surely, 2^{21123213211211} is an apocalyptic number.

21123213211211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123213211211 is an equidigital number, since it uses as much as digits as its factorization.

21123213211211 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 288, while the sum is 23.

Adding to 21123213211211 its reverse (11211231232112), we get a palindrome (32334444443323).

The spelling of 21123213211211 in words is "twenty-one trillion, one hundred twenty-three billion, two hundred thirteen million, two hundred eleven thousand, two hundred eleven".