209440 has 96 divisors (see below), whose sum is σ = 653184. Its totient is φ = 61440.

The previous prime is 209431. The next prime is 209441. The reversal of 209440 is 44902.

209440 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×209440² = 87730227200, which contains 22 as substring.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (209441) by changing a digit.

209440 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12312 + ... + 12328.

It is an arithmetic number, because the mean of its divisors is an integer number (6804).

2²⁰⁹⁴⁴⁰ is an apocalyptic number.

209440 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 209440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (326592).

209440 is an abundant number, since it is smaller than the sum of its proper divisors (443744).

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

209440 is a wasteful number, since it uses less digits than its factorization.

209440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50 (or 42 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 209440 is about 457.6461515188. The cubic root of 209440 is about 59.3863376318.

The spelling of 209440 in words is "two hundred nine thousand, four hundred forty".