20217206205217 has 8 divisors (see below), whose sum is σ = 23105553175296. Its totient is φ = 17328902898912.

The previous prime is 20217206205197. The next prime is 20217206205247. The reversal of 20217206205217 is 71250260271202.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20217206205217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20217206205247) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9917668 + ... + 11781109.

It is an arithmetic number, because the mean of its divisors is an integer number (2888194146912).

Almost surely, 2^{20217206205217} is an apocalyptic number.

It is an amenable number.

20217206205217 is a deficient number, since it is larger than the sum of its proper divisors (2888346970079).

20217206205217 is a wasteful number, since it uses less digits than its factorization.

20217206205217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21831887.

The product of its (nonzero) digits is 47040, while the sum is 37.

Adding to 20217206205217 its reverse (71250260271202), we get a palindrome (91467466476419).

The spelling of 20217206205217 in words is "twenty trillion, two hundred seventeen billion, two hundred six million, two hundred five thousand, two hundred seventeen".