705809 has 4 divisors (see below), whose sum is σ = 760116. Its totient is φ = 651504.

The previous prime is 705787. The next prime is 705821. The reversal of 705809 is 908507.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 908507 = 809 ⋅1123.

It can be written as a sum of positive squares in 2 ways, for example, as 483025 + 222784 = 695^2 + 472^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-705809 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 705809.

It is not an unprimeable number, because it can be changed into a prime (705829) 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, 27134 + ... + 27159.

It is an arithmetic number, because the mean of its divisors is an integer number (190029).

2⁷⁰⁵⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

705809 is a deficient number, since it is larger than the sum of its proper divisors (54307).

705809 is a wasteful number, since it uses less digits than its factorization.

705809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54306.

The product of its (nonzero) digits is 2520, while the sum is 29.

The square root of 705809 is about 840.1243955510. The cubic root of 705809 is about 89.0353350414.

The spelling of 705809 in words is "seven hundred five thousand, eight hundred nine".