209939 has 2 divisors, whose sum is σ = 209940. Its totient is φ = 209938.

The previous prime is 209929. The next prime is 209953. The reversal of 209939 is 939902.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209939 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (209929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104969 + 104970.

It is an arithmetic number, because the mean of its divisors is an integer number (104970).

2²⁰⁹⁹³⁹ is an apocalyptic number.

209939 is a deficient number, since it is larger than the sum of its proper divisors (1).

209939 is an equidigital number, since it uses as much as digits as its factorization.

209939 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4374, while the sum is 32.

The square root of 209939 is about 458.1910082051. The cubic root of 209939 is about 59.4334637443.

It can be divided in two parts, 209 and 939, that multiplied together give a triangular number (196251 = T₆₂₆).

The spelling of 209939 in words is "two hundred nine thousand, nine hundred thirty-nine".