210505 has 4 divisors (see below), whose sum is σ = 252612. Its totient is φ = 168400.

The previous prime is 210499. The next prime is 210523. The reversal of 210505 is 505012.

210505 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 121104 + 89401 = 348^2 + 299^2 .

It is not a de Polignac number, because 210505 - 2¹¹ = 208457 is a prime.

It is a Smith number, since the sum of its digits (13) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a nialpdrome in base 8.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21046 + ... + 21055.

It is an arithmetic number, because the mean of its divisors is an integer number (63153).

2²¹⁰⁵⁰⁵ is an apocalyptic number.

It is an amenable number.

210505 is a deficient number, since it is larger than the sum of its proper divisors (42107).

210505 is an equidigital number, since it uses as much as digits as its factorization.

210505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42106.

The product of its (nonzero) digits is 50, while the sum is 13.

The square root of 210505 is about 458.8082388101. The cubic root of 210505 is about 59.4868271100.

Adding to 210505 its reverse (505012), we get a palindrome (715517).

The spelling of 210505 in words is "two hundred ten thousand, five hundred five".