216666811 has 8 divisors (see below), whose sum is σ = 220547664. Its totient is φ = 212805120.

The previous prime is 216666799. The next prime is 216666817. The reversal of 216666811 is 118666612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 216666811 - 2²⁵ = 183112379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216666817) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19071 + ... + 28231.

It is an arithmetic number, because the mean of its divisors is an integer number (27568458).

Almost surely, 2^216666811 is an apocalyptic number.

216666811 is a deficient number, since it is larger than the sum of its proper divisors (3880853).

216666811 is an equidigital number, since it uses as much as digits as its factorization.

216666811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9581.

The product of its digits is 20736, while the sum is 37.

The square root of 216666811 is about 14719.6063466385. The cubic root of 216666811 is about 600.6167833392.

The spelling of 216666811 in words is "two hundred sixteen million, six hundred sixty-six thousand, eight hundred eleven".