21221121211811 has 2 divisors, whose sum is σ = 21221121211812. Its totient is φ = 21221121211810.

The previous prime is 21221121211757. The next prime is 21221121211819. The reversal of 21221121211811 is 11811212112212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21221121211811 - 2¹⁰ = 21221121210787 is a prime.

It is not a weakly prime, because it can be changed into another prime (21221121211819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610560605905 + 10610560605906.

It is an arithmetic number, because the mean of its divisors is an integer number (10610560605906).

Almost surely, 2^{21221121211811} is an apocalyptic number.

21221121211811 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221121211811 is an equidigital number, since it uses as much as digits as its factorization.

21221121211811 is an evil number, because the sum of its binary digits is even.

The product of its digits is 256, while the sum is 26.

The spelling of 21221121211811 in words is "twenty-one trillion, two hundred twenty-one billion, one hundred twenty-one million, two hundred eleven thousand, eight hundred eleven".