20217417257 has 2 divisors, whose sum is σ = 20217417258. Its totient is φ = 20217417256.

The previous prime is 20217417247. The next prime is 20217417329. The reversal of 20217417257 is 75271471202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15151394281 + 5066022976 = 123091^2 + 71176^2 .

It is a cyclic number.

It is not a de Polignac number, because 20217417257 - 2¹⁴ = 20217400873 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20217417257.

It is not a weakly prime, because it can be changed into another prime (20217417247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10108708628 + 10108708629.

It is an arithmetic number, because the mean of its divisors is an integer number (10108708629).

Almost surely, 2^20217417257 is an apocalyptic number.

It is an amenable number.

20217417257 is a deficient number, since it is larger than the sum of its proper divisors (1).

20217417257 is an equidigital number, since it uses as much as digits as its factorization.

20217417257 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 54880, while the sum is 38.

Adding to 20217417257 its reverse (75271471202), we get a palindrome (95488888459).

The spelling of 20217417257 in words is "twenty billion, two hundred seventeen million, four hundred seventeen thousand, two hundred fifty-seven".