216989 has 4 divisors (see below), whose sum is σ = 219324. Its totient is φ = 214656.

The previous prime is 216973. The next prime is 216991. The reversal of 216989 is 989612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 136900 + 80089 = 370^2 + 283^2 .

It is a cyclic number.

It is not a de Polignac number, because 216989 - 2⁴ = 216973 is a prime.

It is a super-2 number, since 2×216989² = 94168452242, which contains 22 as substring.

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

It is a Duffinian number.

It is a plaindrome in base 15.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 216989.

It is not an unprimeable number, because it can be changed into a prime (216919) 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, 1022 + ... + 1215.

It is an arithmetic number, because the mean of its divisors is an integer number (54831).

2²¹⁶⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

216989 is a deficient number, since it is larger than the sum of its proper divisors (2335).

216989 is an equidigital number, since it uses as much as digits as its factorization.

216989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2334.

The product of its digits is 7776, while the sum is 35.

The square root of 216989 is about 465.8207809877. The cubic root of 216989 is about 60.0914346650.

The spelling of 216989 in words is "two hundred sixteen thousand, nine hundred eighty-nine".