20808481 has 2 divisors, whose sum is σ = 20808482. Its totient is φ = 20808480.

The previous prime is 20808479. The next prime is 20808497. The reversal of 20808481 is 18480802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17986081 + 2822400 = 4241^2 + 1680^2 .

It is a cyclic number.

It is not a de Polignac number, because 20808481 - 2¹ = 20808479 is a prime.

It is a super-2 number, since 2×20808481² = 865985763054722, which contains 22 as substring.

Together with 20808479, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20808421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10404240 + 10404241.

It is an arithmetic number, because the mean of its divisors is an integer number (10404241).

Almost surely, 2^20808481 is an apocalyptic number.

It is an amenable number.

20808481 is a deficient number, since it is larger than the sum of its proper divisors (1).

20808481 is an equidigital number, since it uses as much as digits as its factorization.

20808481 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4096, while the sum is 31.

The square root of 20808481 is about 4561.6313967702. The cubic root of 20808481 is about 275.0511464097.

The spelling of 20808481 in words is "twenty million, eight hundred eight thousand, four hundred eighty-one".