217308643 has 12 divisors (see below), whose sum is σ = 230017320. Its totient is φ = 205271136.

The previous prime is 217308601. The next prime is 217308647. The reversal of 217308643 is 346803712.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-217308643 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 217308599 and 217308608.

It is not an unprimeable number, because it can be changed into a prime (217308647) 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 in 11 ways as a sum of consecutive naturals, for example, 167943 + ... + 169231.

It is an arithmetic number, because the mean of its divisors is an integer number (19168110).

Almost surely, 2^217308643 is an apocalyptic number.

217308643 is a deficient number, since it is larger than the sum of its proper divisors (12708677).

217308643 is a wasteful number, since it uses less digits than its factorization.

217308643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1794 (or 1775 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 34.

The square root of 217308643 is about 14741.3921662779. The cubic root of 217308643 is about 601.2092676305.

The spelling of 217308643 in words is "two hundred seventeen million, three hundred eight thousand, six hundred forty-three".