217684765489 has 3 divisors (see below), whose sum is σ = 217685232057. Its totient is φ = 217684298922.

The previous prime is 217684765469. The next prime is 217684765567. The reversal of 217684765489 is 984567486712.

The square root of 217684765489 is 466567.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 217684765489 - 2³⁵ = 183325027121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217684765469) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 233284 + ... + 699850.

It is an arithmetic number, because the mean of its divisors is an integer number (72561744019).

Almost surely, 2^217684765489 is an apocalyptic number.

217684765489 is the 466567-th square number.

217684765489 is the 233284-th centered octagonal number.

It is an amenable number.

217684765489 is a deficient number, since it is larger than the sum of its proper divisors (466568).

217684765489 is an frugal number, since it uses more digits than its factorization.

217684765489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 933134 (or 466567 counting only the distinct ones).

The product of its digits is 162570240, while the sum is 67.

The spelling of 217684765489 in words is "two hundred seventeen billion, six hundred eighty-four million, seven hundred sixty-five thousand, four hundred eighty-nine".