210805 has 16 divisors (see below), whose sum is σ = 305280. Its totient is φ = 136512.

The previous prime is 210803. The next prime is 210809. The reversal of 210805 is 508012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 210805 - 2¹ = 210803 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210803) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 507 + ... + 823.

It is an arithmetic number, because the mean of its divisors is an integer number (19080).

2²¹⁰⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

210805 is a deficient number, since it is larger than the sum of its proper divisors (94475).

210805 is a wasteful number, since it uses less digits than its factorization.

210805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 348.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 210805 is about 459.1350563832. The cubic root of 210805 is about 59.5150728003.

Adding to 210805 its reverse (508012), we get a palindrome (718817).

The spelling of 210805 in words is "two hundred ten thousand, eight hundred five".