20808506881 has 2 divisors, whose sum is σ = 20808506882. Its totient is φ = 20808506880.

The previous prime is 20808506879. The next prime is 20808506947. The reversal of 20808506881 is 18860580802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19999616400 + 808890481 = 141420^2 + 28441^2 .

It is a cyclic number.

It is not a de Polignac number, because 20808506881 - 2¹ = 20808506879 is a prime.

It is a super-2 number, since 2×20808506881² (a number of 21 digits) contains 22 as substring.

Together with 20808506879, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20808506281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10404253440 + 10404253441.

It is an arithmetic number, because the mean of its divisors is an integer number (10404253441).

Almost surely, 2^20808506881 is an apocalyptic number.

It is an amenable number.

20808506881 is a deficient number, since it is larger than the sum of its proper divisors (1).

20808506881 is an equidigital number, since it uses as much as digits as its factorization.

20808506881 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 245760, while the sum is 46.

The spelling of 20808506881 in words is "twenty billion, eight hundred eight million, five hundred six thousand, eight hundred eighty-one".