216709 has 4 divisors (see below), whose sum is σ = 222604. Its totient is φ = 210816.

The previous prime is 216703. The next prime is 216719. The reversal of 216709 is 907612.

216709 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.

It can be written as a sum of positive squares in 2 ways, for example, as 199809 + 16900 = 447^2 + 130^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216709 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216703) 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, 2892 + ... + 2965.

It is an arithmetic number, because the mean of its divisors is an integer number (55651).

2²¹⁶⁷⁰⁹ is an apocalyptic number.

It is an amenable number.

216709 is a deficient number, since it is larger than the sum of its proper divisors (5895).

216709 is an equidigital number, since it uses as much as digits as its factorization.

216709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5894.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 216709 is about 465.5201391992. The cubic root of 216709 is about 60.0655764509.

The spelling of 216709 in words is "two hundred sixteen thousand, seven hundred nine".