215609 has 4 divisors (see below), whose sum is σ = 216720. Its totient is φ = 214500.

The previous prime is 215587. The next prime is 215617. The reversal of 215609 is 906512.

215609 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 Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 215609 - 2⁸ = 215353 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (215659) 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, 179 + ... + 680.

It is an arithmetic number, because the mean of its divisors is an integer number (54180).

2²¹⁵⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

215609 is a deficient number, since it is larger than the sum of its proper divisors (1111).

215609 is an equidigital number, since it uses as much as digits as its factorization.

215609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1110.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 215609 is about 464.3371619847. The cubic root of 215609 is about 59.9637744292.

The spelling of 215609 in words is "two hundred fifteen thousand, six hundred nine".