209906838 has 12 divisors (see below), whose sum is σ = 454798188. Its totient is φ = 69968940.

The previous prime is 209906833. The next prime is 209906881. The reversal of 209906838 is 838609902.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 209906793 and 209906802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209906831) 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 in 5 ways as a sum of consecutive naturals, for example, 5830728 + ... + 5830763.

It is an arithmetic number, because the mean of its divisors is an integer number (37899849).

Almost surely, 2^209906838 is an apocalyptic number.

209906838 is an abundant number, since it is smaller than the sum of its proper divisors (244891350).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

209906838 is a wasteful number, since it uses less digits than its factorization.

209906838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11661499 (or 11661496 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The square root of 209906838 is about 14488.1619952291. The cubic root of 209906838 is about 594.3042858218.

The spelling of 209906838 in words is "two hundred nine million, nine hundred six thousand, eight hundred thirty-eight".