209643138 has 12 divisors (see below), whose sum is σ = 454226838. Its totient is φ = 69881040.

The previous prime is 209643121. The next prime is 209643139. The reversal of 209643138 is 831346902.

209643138 is a `hidden beast` number, since 2 + 0 + 9 + 643 + 1 + 3 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 157326849 + 52316289 = 12543^2 + 7233^2 .

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (209643139) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5823403 + ... + 5823438.

Almost surely, 2^209643138 is an apocalyptic number.

209643138 is an abundant number, since it is smaller than the sum of its proper divisors (244583700).

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

209643138 is a wasteful number, since it uses less digits than its factorization.

209643138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11646849 (or 11646846 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 209643138 is about 14479.0586019948. The cubic root of 209643138 is about 594.0553123339.

The spelling of 209643138 in words is "two hundred nine million, six hundred forty-three thousand, one hundred thirty-eight".