217681768 has 8 divisors (see below), whose sum is σ = 408153330. Its totient is φ = 108840880.

The previous prime is 217681757. The next prime is 217681771. The reversal of 217681768 is 867186712.

It can be written as a sum of positive squares in only one way, i.e., 195384484 + 22297284 = 13978^2 + 4722^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13605103 + ... + 13605118.

Almost surely, 2^217681768 is an apocalyptic number.

It is an amenable number.

217681768 is a deficient number, since it is larger than the sum of its proper divisors (190471562).

217681768 is a wasteful number, since it uses less digits than its factorization.

217681768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27210227 (or 27210223 counting only the distinct ones).

The product of its digits is 225792, while the sum is 46.

The square root of 217681768 is about 14754.0424291107. The cubic root of 217681768 is about 601.5531685690.

The spelling of 217681768 in words is "two hundred seventeen million, six hundred eighty-one thousand, seven hundred sixty-eight".