217798350491 has 2 divisors, whose sum is σ = 217798350492. Its totient is φ = 217798350490.

The previous prime is 217798350487. The next prime is 217798350499. The reversal of 217798350491 is 194053897712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 217798350491 - 2² = 217798350487 is a prime.

It is a super-2 number, since 2×217798350491² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (217798350499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108899175245 + 108899175246.

It is an arithmetic number, because the mean of its divisors is an integer number (108899175246).

Almost surely, 2^217798350491 is an apocalyptic number.

217798350491 is a deficient number, since it is larger than the sum of its proper divisors (1).

217798350491 is an equidigital number, since it uses as much as digits as its factorization.

217798350491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3810240, while the sum is 56.

The spelling of 217798350491 in words is "two hundred seventeen billion, seven hundred ninety-eight million, three hundred fifty thousand, four hundred ninety-one".