216985665 has 16 divisors (see below), whose sum is σ = 373883328. Its totient is φ = 106823616.

The previous prime is 216985661. The next prime is 216985667. The reversal of 216985665 is 566589612.

216985665 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 216985665 - 2² = 216985661 is a prime.

It is not an unprimeable number, because it can be changed into a prime (216985661) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 556179 + ... + 556568.

It is an arithmetic number, because the mean of its divisors is an integer number (23367708).

Almost surely, 2^216985665 is an apocalyptic number.

It is an amenable number.

216985665 is a deficient number, since it is larger than the sum of its proper divisors (156897663).

216985665 is a wasteful number, since it uses less digits than its factorization.

216985665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1112768.

The product of its digits is 777600, while the sum is 48.

The square root of 216985665 is about 14730.4332930162. The cubic root of 216985665 is about 600.9112680613.

The spelling of 216985665 in words is "two hundred sixteen million, nine hundred eighty-five thousand, six hundred sixty-five".