217798748891 has 2 divisors, whose sum is σ = 217798748892. Its totient is φ = 217798748890.

The previous prime is 217798748737. The next prime is 217798748897. The reversal of 217798748891 is 198847897712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 217798748891 - 2³⁰ = 216725007067 is a prime.

It is not a weakly prime, because it can be changed into another prime (217798748897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108899374445 + 108899374446.

It is an arithmetic number, because the mean of its divisors is an integer number (108899374446).

Almost surely, 2^217798748891 is an apocalyptic number.

217798748891 is a deficient number, since it is larger than the sum of its proper divisors (1).

217798748891 is an equidigital number, since it uses as much as digits as its factorization.

217798748891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 113799168, while the sum is 71.

The spelling of 217798748891 in words is "two hundred seventeen billion, seven hundred ninety-eight million, seven hundred forty-eight thousand, eight hundred ninety-one".