20806455869 has 2 divisors, whose sum is σ = 20806455870. Its totient is φ = 20806455868.

The previous prime is 20806455827. The next prime is 20806455871. The reversal of 20806455869 is 96855460802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20789890969 + 16564900 = 144187^2 + 4070^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20806455869 is a prime.

It is a super-2 number, since 2×20806455869² (a number of 21 digits) contains 22 as substring.

Together with 20806455871, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20806455869.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20806455889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10403227934 + 10403227935.

It is an arithmetic number, because the mean of its divisors is an integer number (10403227935).

Almost surely, 2^20806455869 is an apocalyptic number.

It is an amenable number.

20806455869 is a deficient number, since it is larger than the sum of its proper divisors (1).

20806455869 is an equidigital number, since it uses as much as digits as its factorization.

20806455869 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4147200, while the sum is 53.

The spelling of 20806455869 in words is "twenty billion, eight hundred six million, four hundred fifty-five thousand, eight hundred sixty-nine".