2100209 has 4 divisors (see below), whose sum is σ = 2172660. Its totient is φ = 2027760.

The previous prime is 2100193. The next prime is 2100221. The reversal of 2100209 is 9020012.

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 1216609 + 883600 = 1103^2 + 940^2 .

It is a cyclic number.

It is not a de Polignac number, because 2100209 - 2⁴ = 2100193 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 2100193 and 2100202.

It is not an unprimeable number, because it can be changed into a prime (2100229) 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, 36182 + ... + 36239.

It is an arithmetic number, because the mean of its divisors is an integer number (543165).

2^2100209 is an apocalyptic number.

2100209 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

2100209 is a deficient number, since it is larger than the sum of its proper divisors (72451).

2100209 is an equidigital number, since it uses as much as digits as its factorization.

2100209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72450.

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 2100209 is about 1449.2097846758. The cubic root of 2100209 is about 128.0621646284.

The spelling of 2100209 in words is "two million, one hundred thousand, two hundred nine".