2118209 has 2 divisors, whose sum is σ = 2118210. Its totient is φ = 2118208.

The previous prime is 2118187. The next prime is 2118239. The reversal of 2118209 is 9028112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1210000 + 908209 = 1100^2 + 953^2 .

It is a cyclic number.

It is not a de Polignac number, because 2118209 - 2⁸ = 2117953 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (2118239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1059104 + 1059105.

It is an arithmetic number, because the mean of its divisors is an integer number (1059105).

2^2118209 is an apocalyptic number.

It is an amenable number.

2118209 is a deficient number, since it is larger than the sum of its proper divisors (1).

2118209 is an equidigital number, since it uses as much as digits as its factorization.

2118209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 2118209 is about 1455.4068159796. The cubic root of 2118209 is about 128.4269798670.

Subtracting 2118209 from its reverse (9028112), we obtain a triangular number (6909903 = T₃₇₁₇).

The spelling of 2118209 in words is "two million, one hundred eighteen thousand, two hundred nine".