78091809 has 8 divisors (see below), whose sum is σ = 107712960. Its totient is φ = 50265936.

The previous prime is 78091807. The next prime is 78091817. The reversal of 78091809 is 90819087.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 78091809 - 2¹ = 78091807 is a prime.

It is not an unprimeable number, because it can be changed into a prime (78091807) 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, 448717 + ... + 448890.

It is an arithmetic number, because the mean of its divisors is an integer number (13464120).

Almost surely, 2^78091809 is an apocalyptic number.

It is an amenable number.

78091809 is a deficient number, since it is larger than the sum of its proper divisors (29621151).

78091809 is a wasteful number, since it uses less digits than its factorization.

78091809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 897639.

The product of its (nonzero) digits is 36288, while the sum is 42.

The square root of 78091809 is about 8836.9569988769. The cubic root of 78091809 is about 427.4334385614.

The spelling of 78091809 in words is "seventy-eight million, ninety-one thousand, eight hundred nine".