210091 has 4 divisors (see below), whose sum is σ = 240112. Its totient is φ = 180072.

The previous prime is 210071. The next prime is 210097. The reversal of 210091 is 190012.

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

It is a cyclic number.

It is not a de Polignac number, because 210091 - 2⁹ = 209579 is a prime.

It is a Duffinian number.

210091 is a lucky number.

It is a plaindrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (210097) 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, 15000 + ... + 15013.

It is an arithmetic number, because the mean of its divisors is an integer number (60028).

2²¹⁰⁰⁹¹ is an apocalyptic number.

210091 is a deficient number, since it is larger than the sum of its proper divisors (30021).

210091 is an equidigital number, since it uses as much as digits as its factorization.

210091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30020.

The product of its (nonzero) digits is 18, while the sum is 13.

The square root of 210091 is about 458.3568478816. The cubic root of 210091 is about 59.4478039528.

The spelling of 210091 in words is "two hundred ten thousand, ninety-one".