78609909 has 16 divisors (see below), whose sum is σ = 120952832. Its totient is φ = 44482608.

The previous prime is 78609901. The next prime is 78609943. The reversal of 78609909 is 90990687.

It is a happy number.

It is not a de Polignac number, because 78609909 - 2³ = 78609901 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78609901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16009 + ... + 20334.

It is an arithmetic number, because the mean of its divisors is an integer number (7559552).

Almost surely, 2^78609909 is an apocalyptic number.

It is an amenable number.

78609909 is a deficient number, since it is larger than the sum of its proper divisors (42342923).

78609909 is a wasteful number, since it uses less digits than its factorization.

78609909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36456.

The product of its (nonzero) digits is 244944, while the sum is 48.

The square root of 78609909 is about 8866.2229274929. Note that the first 3 decimals coincide. The cubic root of 78609909 is about 428.3766246255.

The spelling of 78609909 in words is "seventy-eight million, six hundred nine thousand, nine hundred nine".