21011122122811 has 2 divisors, whose sum is σ = 21011122122812. Its totient is φ = 21011122122810.

The previous prime is 21011122122787. The next prime is 21011122122817. The reversal of 21011122122811 is 11822122111012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21011122122811 - 2²⁹ = 21010585251899 is a prime.

It is not a weakly prime, because it can be changed into another prime (21011122122817) 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, 10505561061405 + 10505561061406.

It is an arithmetic number, because the mean of its divisors is an integer number (10505561061406).

Almost surely, 2^{21011122122811} is an apocalyptic number.

21011122122811 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011122122811 is an equidigital number, since it uses as much as digits as its factorization.

21011122122811 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21011122122811 its reverse (11822122111012), we get a palindrome (32833244233823).

The spelling of 21011122122811 in words is "twenty-one trillion, eleven billion, one hundred twenty-two million, one hundred twenty-two thousand, eight hundred eleven".