216811 has 8 divisors (see below), whose sum is σ = 253440. Its totient is φ = 181608.

The previous prime is 216803. The next prime is 216829. The reversal of 216811 is 118612.

216811 is a nontrivial binomial coefficient, being equal to C(659, 2).

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

It is not a de Polignac number, because 216811 - 2³ = 216803 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216841) 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, 1 + ... + 658.

It is an arithmetic number, because the mean of its divisors is an integer number (31680).

2²¹⁶⁸¹¹ is an apocalyptic number.

216811 is the 658-th triangular number.

216811 is the 220-th centered nonagonal number.

216811 is a deficient number, since it is larger than the sum of its proper divisors (36629).

216811 is an equidigital number, since it uses as much as digits as its factorization.

216811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 713.

The product of its digits is 96, while the sum is 19.

The square root of 216811 is about 465.6296811845. The cubic root of 216811 is about 60.0749988065.

The spelling of 216811 in words is "two hundred sixteen thousand, eight hundred eleven".