217558404855797 has 2 divisors, whose sum is σ = 217558404855798. Its totient is φ = 217558404855796.

The previous prime is 217558404855641. The next prime is 217558404855851. The reversal of 217558404855797 is 797558404855712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 161392988034916 + 56165416820881 = 12704054^2 + 7494359^2 .

It is a cyclic number.

It is not a de Polignac number, because 217558404855797 - 2¹⁰ = 217558404854773 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217558404851797) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108779202427898 + 108779202427899.

It is an arithmetic number, because the mean of its divisors is an integer number (108779202427899).

Almost surely, 2^{217558404855797} is an apocalyptic number.

It is an amenable number.

217558404855797 is a deficient number, since it is larger than the sum of its proper divisors (1).

217558404855797 is an equidigital number, since it uses as much as digits as its factorization.

217558404855797 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3951360000, while the sum is 77.

The spelling of 217558404855797 in words is "two hundred seventeen trillion, five hundred fifty-eight billion, four hundred four million, eight hundred fifty-five thousand, seven hundred ninety-seven".