78646009 has 8 divisors (see below), whose sum is σ = 85199240. Its totient is φ = 72594288.

The previous prime is 78646003. The next prime is 78646013. The reversal of 78646009 is 90064687.

It can be written as a sum of positive squares in 4 ways, for example, as 43599609 + 35046400 = 6603^2 + 5920^2 .

It is not a de Polignac number, because 78646009 - 2¹⁷ = 78514937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78646003) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15702 + ... + 20095.

It is an arithmetic number, because the mean of its divisors is an integer number (10649905).

Almost surely, 2^78646009 is an apocalyptic number.

It is an amenable number.

78646009 is a deficient number, since it is larger than the sum of its proper divisors (6553231).

78646009 is an equidigital number, since it uses as much as digits as its factorization.

78646009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35836 (or 35810 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 40.

The square root of 78646009 is about 8868.2585099894. The cubic root of 78646009 is about 428.4421890041.

The spelling of 78646009 in words is "seventy-eight million, six hundred forty-six thousand, nine".