217620711257 has 2 divisors, whose sum is σ = 217620711258. Its totient is φ = 217620711256.

The previous prime is 217620711167. The next prime is 217620711289. The reversal of 217620711257 is 752117026712.

217620711257 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 172294727056 + 45325984201 = 415084^2 + 212899^2 .

It is a cyclic number.

It is not a de Polignac number, because 217620711257 - 2²⁸ = 217352275801 is a prime.

It is not a weakly prime, because it can be changed into another prime (217620713257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108810355628 + 108810355629.

It is an arithmetic number, because the mean of its divisors is an integer number (108810355629).

Almost surely, 2^217620711257 is an apocalyptic number.

It is an amenable number.

217620711257 is a deficient number, since it is larger than the sum of its proper divisors (1).

217620711257 is an equidigital number, since it uses as much as digits as its factorization.

217620711257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 82320, while the sum is 41.

Adding to 217620711257 its reverse (752117026712), we get a palindrome (969737737969).

The spelling of 217620711257 in words is "two hundred seventeen billion, six hundred twenty million, seven hundred eleven thousand, two hundred fifty-seven".