216665911 has 64 divisors (see below), whose sum is σ = 305233920. Its totient is φ = 148642560.

The previous prime is 216665903. The next prime is 216665921. The reversal of 216665911 is 119566612.

It is not a de Polignac number, because 216665911 - 2³ = 216665903 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216665921) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1581435 + ... + 1581571.

It is an arithmetic number, because the mean of its divisors is an integer number (4769280).

Almost surely, 2^216665911 is an apocalyptic number.

216665911 is a deficient number, since it is larger than the sum of its proper divisors (88568009).

216665911 is a wasteful number, since it uses less digits than its factorization.

216665911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244.

The product of its digits is 19440, while the sum is 37.

The square root of 216665911 is about 14719.5757751370. The cubic root of 216665911 is about 600.6159517154.

The spelling of 216665911 in words is "two hundred sixteen million, six hundred sixty-five thousand, nine hundred eleven".