78805 has 4 divisors (see below), whose sum is σ = 94572. Its totient is φ = 63040.

The previous prime is 78803. The next prime is 78809. The reversal of 78805 is 50887.

78805 = 198² + 199².

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50887 = 151 ⋅337.

It can be written as a sum of positive squares in 2 ways, for example, as 39204 + 39601 = 198^2 + 199^2 .

It is not a de Polignac number, because 78805 - 2¹ = 78803 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 (78803) 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, 7876 + ... + 7885.

It is an arithmetic number, because the mean of its divisors is an integer number (23643).

2⁷⁸⁸⁰⁵ is an apocalyptic number.

78805 is the 199-th centered square number.

It is an amenable number.

78805 is a deficient number, since it is larger than the sum of its proper divisors (15767).

78805 is a wasteful number, since it uses less digits than its factorization.

78805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15766.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 78805 is about 280.7222826923. The cubic root of 78805 is about 42.8730707992.

The spelling of 78805 in words is "seventy-eight thousand, eight hundred five".