209139984 has 120 divisors (see below), whose sum is σ = 636756120. Its totient is φ = 63811584.

The previous prime is 209139971. The next prime is 209139991. The reversal of 209139984 is 489931902.

It can be written as a sum of positive squares in 4 ways, for example, as 138579984 + 70560000 = 11772^2 + 8400^2 .

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 89422 + ... + 91730.

It is an arithmetic number, because the mean of its divisors is an integer number (5306301).

Almost surely, 2^209139984 is an apocalyptic number.

209139984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 209139984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (318378060).

209139984 is an abundant number, since it is smaller than the sum of its proper divisors (427616136).

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

209139984 is a wasteful number, since it uses less digits than its factorization.

209139984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2377 (or 2368 counting only the distinct ones).

The product of its (nonzero) digits is 139968, while the sum is 45.

The square root of 209139984 is about 14461.6729322717. The cubic root of 209139984 is about 593.5796774767.

The spelling of 209139984 in words is "two hundred nine million, one hundred thirty-nine thousand, nine hundred eighty-four".