20209347666917 has 2 divisors, whose sum is σ = 20209347666918. Its totient is φ = 20209347666916.

The previous prime is 20209347666913. The next prime is 20209347666961. The reversal of 20209347666917 is 71966674390202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10934192142721 + 9275155524196 = 3306689^2 + 3045514^2 .

It is a cyclic number.

It is not a de Polignac number, because 20209347666917 - 2² = 20209347666913 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20209347666917.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20209347666913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10104673833458 + 10104673833459.

It is an arithmetic number, because the mean of its divisors is an integer number (10104673833459).

Almost surely, 2^{20209347666917} is an apocalyptic number.

It is an amenable number.

20209347666917 is a deficient number, since it is larger than the sum of its proper divisors (1).

20209347666917 is an equidigital number, since it uses as much as digits as its factorization.

20209347666917 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 41150592, while the sum is 62.

The spelling of 20209347666917 in words is "twenty trillion, two hundred nine billion, three hundred forty-seven million, six hundred sixty-six thousand, nine hundred seventeen".