78085909 has 4 divisors (see below), whose sum is σ = 85184640. Its totient is φ = 70987180.

The previous prime is 78085901. The next prime is 78085927. The reversal of 78085909 is 90958087.

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, and also an emirpimes, since its reverse is a distinct semiprime: 90958087 = 11 ⋅8268917.

It is not a de Polignac number, because 78085909 - 2³ = 78085901 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78085901) 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, 3549349 + ... + 3549370.

It is an arithmetic number, because the mean of its divisors is an integer number (21296160).

Almost surely, 2^78085909 is an apocalyptic number.

It is an amenable number.

78085909 is a deficient number, since it is larger than the sum of its proper divisors (7098731).

78085909 is a wasteful number, since it uses less digits than its factorization.

78085909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7098730.

The product of its (nonzero) digits is 181440, while the sum is 46.

The square root of 78085909 is about 8836.6231672512. The cubic root of 78085909 is about 427.4226737927.

The spelling of 78085909 in words is "seventy-eight million, eighty-five thousand, nine hundred nine".