623809 has 4 divisors (see below), whose sum is σ = 626116. Its totient is φ = 621504.

The previous prime is 623803. The next prime is 623839. The reversal of 623809 is 908326.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 172225 + 451584 = 415^2 + 672^2 .

It is a cyclic number.

It is not a de Polignac number, because 623809 - 2⁷ = 623681 is a prime.

It is a Duffinian number.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (623803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 684 + ... + 1309.

It is an arithmetic number, because the mean of its divisors is an integer number (156529).

2⁶²³⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

623809 is a deficient number, since it is larger than the sum of its proper divisors (2307).

623809 is a wasteful number, since it uses less digits than its factorization.

623809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2306.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 623809 is about 789.8158013107. The cubic root of 623809 is about 85.4444539642. Note that the first 4 decimals are identical.

The spelling of 623809 in words is "six hundred twenty-three thousand, eight hundred nine".