78807809 has 6 divisors (see below), whose sum is σ = 79778070. Its totient is φ = 77839520.

The previous prime is 78807803. The next prime is 78807811. The reversal of 78807809 is 90870887.

It can be written as a sum of positive squares in 3 ways, for example, as 9168784 + 69639025 = 3028^2 + 8345^2 .

It is not a de Polignac number, because 78807809 - 2²⁰ = 77759233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78807803) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 83279 + ... + 84219.

It is an arithmetic number, because the mean of its divisors is an integer number (13296345).

Almost surely, 2^78807809 is an apocalyptic number.

It is an amenable number.

78807809 is a deficient number, since it is larger than the sum of its proper divisors (970261).

78807809 is an frugal number, since it uses more digits than its factorization.

78807809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1971 (or 1030 counting only the distinct ones).

The product of its (nonzero) digits is 225792, while the sum is 47.

The square root of 78807809 is about 8877.3762452653. The cubic root of 78807809 is about 428.7358019591.

The spelling of 78807809 in words is "seventy-eight million, eight hundred seven thousand, eight hundred nine".