209889940 has 48 divisors (see below), whose sum is σ = 476597520. Its totient is φ = 77184000.

The previous prime is 209889931. The next prime is 209889943. The reversal of 209889940 is 49988902.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 50069776 + 159820164 = 7076^2 + 12642^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209889943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 68440 + ... + 71440.

It is an arithmetic number, because the mean of its divisors is an integer number (9929115).

Almost surely, 2^209889940 is an apocalyptic number.

209889940 is a gapful number since it is divisible by the number (20) 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 209889940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (238298760).

209889940 is an abundant number, since it is smaller than the sum of its proper divisors (266707580).

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

209889940 is a wasteful number, since it uses less digits than its factorization.

209889940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3292 (or 3290 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 49.

The square root of 209889940 is about 14487.5788177321. The cubic root of 209889940 is about 594.2883377574.

The spelling of 209889940 in words is "two hundred nine million, eight hundred eighty-nine thousand, nine hundred forty".