18978879282217 has 2 divisors, whose sum is σ = 18978879282218. Its totient is φ = 18978879282216.

The previous prime is 18978879282157. The next prime is 18978879282227. The reversal of 18978879282217 is 71228297887981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9661025351961 + 9317853930256 = 3108219^2 + 3052516^2 .

It is a cyclic number.

It is not a de Polignac number, because 18978879282217 - 2¹¹ = 18978879280169 is a prime.

It is not a weakly prime, because it can be changed into another prime (18978879282227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9489439641108 + 9489439641109.

It is an arithmetic number, because the mean of its divisors is an integer number (9489439641109).

Almost surely, 2^{18978879282217} is an apocalyptic number.

It is an amenable number.

18978879282217 is a deficient number, since it is larger than the sum of its proper divisors (1).

18978879282217 is an equidigital number, since it uses as much as digits as its factorization.

18978879282217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 910393344, while the sum is 79.

The spelling of 18978879282217 in words is "eighteen trillion, nine hundred seventy-eight billion, eight hundred seventy-nine million, two hundred eighty-two thousand, two hundred seventeen".