216389 has 4 divisors (see below), whose sum is σ = 217356. Its totient is φ = 215424.

The previous prime is 216379. The next prime is 216397. The reversal of 216389 is 983612.

216389 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 28900 + 187489 = 170^2 + 433^2 .

It is a cyclic number.

It is not a de Polignac number, because 216389 - 2⁴ = 216373 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216319) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47 + ... + 659.

It is an arithmetic number, because the mean of its divisors is an integer number (54339).

2²¹⁶³⁸⁹ is an apocalyptic number.

It is an amenable number.

216389 is a deficient number, since it is larger than the sum of its proper divisors (967).

216389 is an equidigital number, since it uses as much as digits as its factorization.

216389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 966.

The product of its digits is 2592, while the sum is 29.

The square root of 216389 is about 465.1763106608. The cubic root of 216389 is about 60.0359969179.

The spelling of 216389 in words is "two hundred sixteen thousand, three hundred eighty-nine".