21281712811 has 2 divisors, whose sum is σ = 21281712812. Its totient is φ = 21281712810.

The previous prime is 21281712791. The next prime is 21281712817. The reversal of 21281712811 is 11821718212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21281712811 - 2²⁹ = 20744841899 is a prime.

It is a super-2 number, since 2×21281712811² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21281712817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10640856405 + 10640856406.

It is an arithmetic number, because the mean of its divisors is an integer number (10640856406).

Almost surely, 2^21281712811 is an apocalyptic number.

21281712811 is a deficient number, since it is larger than the sum of its proper divisors (1).

21281712811 is an equidigital number, since it uses as much as digits as its factorization.

21281712811 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3584, while the sum is 34.

The spelling of 21281712811 in words is "twenty-one billion, two hundred eighty-one million, seven hundred twelve thousand, eight hundred eleven".