217231668 has 18 divisors (see below), whose sum is σ = 549113474. Its totient is φ = 72410544.

The previous prime is 217231633. The next prime is 217231669. The reversal of 217231668 is 866132712.

217231668 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 210482064 + 6749604 = 14508^2 + 2598^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 6034213 = 217231668 / (2 + 1 + 7 + 2 + 3 + 1 + 6 + 6 + 8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217231669) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3017071 + ... + 3017142.

Almost surely, 2^217231668 is an apocalyptic number.

It is an amenable number.

217231668 is an abundant number, since it is smaller than the sum of its proper divisors (331881806).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

217231668 is a wasteful number, since it uses less digits than its factorization.

217231668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6034223 (or 6034218 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 217231668 is about 14738.7810893574. The cubic root of 217231668 is about 601.1382725272.

The spelling of 217231668 in words is "two hundred seventeen million, two hundred thirty-one thousand, six hundred sixty-eight".