78086809 has 4 divisors (see below), whose sum is σ = 78364980. Its totient is φ = 77808640.

The previous prime is 78086807. The next prime is 78086851. The reversal of 78086809 is 90868087.

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 51337225 + 26749584 = 7165^2 + 5172^2 .

It is a cyclic number.

It is not a de Polignac number, because 78086809 - 2¹ = 78086807 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78086803) 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, 138664 + ... + 139225.

It is an arithmetic number, because the mean of its divisors is an integer number (19591245).

Almost surely, 2^78086809 is an apocalyptic number.

It is an amenable number.

78086809 is a deficient number, since it is larger than the sum of its proper divisors (278171).

78086809 is a wasteful number, since it uses less digits than its factorization.

78086809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278170.

The product of its (nonzero) digits is 193536, while the sum is 46.

The square root of 78086809 is about 8836.6740915347. The cubic root of 78086809 is about 427.4243159111.

The spelling of 78086809 in words is "seventy-eight million, eighty-six thousand, eight hundred nine".