20636665717 has 2 divisors, whose sum is σ = 20636665718. Its totient is φ = 20636665716.

The previous prime is 20636665667. The next prime is 20636665747. The reversal of 20636665717 is 71756663602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18441368401 + 2195297316 = 135799^2 + 46854^2 .

It is a cyclic number.

It is not a de Polignac number, because 20636665717 - 2⁷ = 20636665589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20636665747) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10318332858 + 10318332859.

It is an arithmetic number, because the mean of its divisors is an integer number (10318332859).

Almost surely, 2^20636665717 is an apocalyptic number.

It is an amenable number.

20636665717 is a deficient number, since it is larger than the sum of its proper divisors (1).

20636665717 is an equidigital number, since it uses as much as digits as its factorization.

20636665717 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1905120, while the sum is 49.

The spelling of 20636665717 in words is "twenty billion, six hundred thirty-six million, six hundred sixty-five thousand, seven hundred seventeen".