78609 has 4 divisors (see below), whose sum is σ = 104816. Its totient is φ = 52404.

The previous prime is 78607. The next prime is 78623. The reversal of 78609 is 90687.

It is a happy number.

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.

It is not a de Polignac number, because 78609 - 2¹ = 78607 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (78607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13099 + ... + 13104.

It is an arithmetic number, because the mean of its divisors is an integer number (26204).

2⁷⁸⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

78609 is a deficient number, since it is larger than the sum of its proper divisors (26207).

78609 is a wasteful number, since it uses less digits than its factorization.

78609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26206.

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 78609 is about 280.3729658865. The cubic root of 78609 is about 42.8374973452.

The spelling of 78609 in words is "seventy-eight thousand, six hundred nine".