213805 has 8 divisors (see below), whose sum is σ = 261144. Its totient is φ = 168000.

The previous prime is 213799. The next prime is 213821. The reversal of 213805 is 508312.

It is a happy number.

213805 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 10404 + 203401 = 102^2 + 451^2 .

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

It is a de Polignac number, because none of the positive numbers 2^k-213805 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 46 + ... + 655.

It is an arithmetic number, because the mean of its divisors is an integer number (32643).

2²¹³⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

213805 is a deficient number, since it is larger than the sum of its proper divisors (47339).

213805 is an equidigital number, since it uses as much as digits as its factorization.

213805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 767.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 213805 is about 462.3905275846. The cubic root of 213805 is about 59.7960668994.

The spelling of 213805 in words is "two hundred thirteen thousand, eight hundred five".