78146809 has 4 divisors (see below), whose sum is σ = 84158116. Its totient is φ = 72135504.

The previous prime is 78146797. The next prime is 78146813. The reversal of 78146809 is 90864187.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90864187 = 163 ⋅557449.

It can be written as a sum of positive squares in 2 ways, for example, as 35283600 + 42863209 = 5940^2 + 6547^2 .

It is a cyclic number.

It is not a de Polignac number, because 78146809 - 2⁵ = 78146777 is a prime.

It is a super-2 number, since 2×78146809² = 12213847513764962, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78146869) 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, 3005634 + ... + 3005659.

It is an arithmetic number, because the mean of its divisors is an integer number (21039529).

Almost surely, 2^78146809 is an apocalyptic number.

It is an amenable number.

78146809 is a deficient number, since it is larger than the sum of its proper divisors (6011307).

78146809 is a wasteful number, since it uses less digits than its factorization.

78146809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6011306.

The product of its (nonzero) digits is 96768, while the sum is 43.

The square root of 78146809 is about 8840.0683820885. The cubic root of 78146809 is about 427.5337620247.

The spelling of 78146809 in words is "seventy-eight million, one hundred forty-six thousand, eight hundred nine".