209971243 has 2 divisors, whose sum is σ = 209971244. Its totient is φ = 209971242.

The previous prime is 209971241. The next prime is 209971249. The reversal of 209971243 is 342179902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 209971243 - 2¹ = 209971241 is a prime.

Together with 209971241, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (209971241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104985621 + 104985622.

It is an arithmetic number, because the mean of its divisors is an integer number (104985622).

Almost surely, 2^209971243 is an apocalyptic number.

209971243 is a deficient number, since it is larger than the sum of its proper divisors (1).

209971243 is an equidigital number, since it uses as much as digits as its factorization.

209971243 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27216, while the sum is 37.

The square root of 209971243 is about 14490.3845014547. The cubic root of 209971243 is about 594.3650623928.

The spelling of 209971243 in words is "two hundred nine million, nine hundred seventy-one thousand, two hundred forty-three".