217918079 has 2 divisors, whose sum is σ = 217918080. Its totient is φ = 217918078.

The previous prime is 217918069. The next prime is 217918097. The reversal of 217918079 is 970819712.

Together with next prime (217918097) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-217918079 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217918039) 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, 108959039 + 108959040.

It is an arithmetic number, because the mean of its divisors is an integer number (108959040).

Almost surely, 2^217918079 is an apocalyptic number.

217918079 is a deficient number, since it is larger than the sum of its proper divisors (1).

217918079 is an equidigital number, since it uses as much as digits as its factorization.

217918079 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 63504, while the sum is 44.

The square root of 217918079 is about 14762.0486044451. The cubic root of 217918079 is about 601.7707679013.

The spelling of 217918079 in words is "two hundred seventeen million, nine hundred eighteen thousand, seventy-nine".