209818243 has 2 divisors, whose sum is σ = 209818244. Its totient is φ = 209818242.

The previous prime is 209818241. The next prime is 209818289. The reversal of 209818243 is 342818902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 209818243 - 2¹ = 209818241 is a prime.

Together with 209818241, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (209818241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104909121 + 104909122.

It is an arithmetic number, because the mean of its divisors is an integer number (104909122).

Almost surely, 2^209818243 is an apocalyptic number.

209818243 is a deficient number, since it is larger than the sum of its proper divisors (1).

209818243 is an equidigital number, since it uses as much as digits as its factorization.

209818243 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27648, while the sum is 37.

The square root of 209818243 is about 14485.1041763599. The cubic root of 209818243 is about 594.2206617435.

The spelling of 209818243 in words is "two hundred nine million, eight hundred eighteen thousand, two hundred forty-three".