209920 has 44 divisors (see below), whose sum is σ = 515844. Its totient is φ = 81920.

The previous prime is 209917. The next prime is 209927. The reversal of 209920 is 29902.

209920 = T₈₀ + T₈₁ + ... + T₁₂₀.

It can be written as a sum of positive squares in 2 ways, for example, as 36864 + 173056 = 192^2 + 416^2 .

It is a nialpdrome in base 8.

It is a junction number, because it is equal to n+sod(n) for n = 209891 and 209900.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5100 + ... + 5140.

2²⁰⁹⁹²⁰ is an apocalyptic number.

209920 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 209920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (257922).

209920 is an abundant number, since it is smaller than the sum of its proper divisors (305924).

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

209920 is an equidigital number, since it uses as much as digits as its factorization.

209920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66 (or 48 counting only the distinct ones).

The product of its (nonzero) digits is 324, while the sum is 22.

The square root of 209920 is about 458.1702740248. The cubic root of 209920 is about 59.4316707316.

The spelling of 209920 in words is "two hundred nine thousand, nine hundred twenty".