209808040 has 64 divisors (see below), whose sum is σ = 525949200. Its totient is φ = 74790912.

The previous prime is 209808037. The next prime is 209808041. The reversal of 209808040 is 40808902.

It can be written as a sum of positive squares in 8 ways, for example, as 67864644 + 141943396 = 8238^2 + 11914^2 .

It is a junction number, because it is equal to n+sod(n) for n = 209807993 and 209808011.

It is not an unprimeable number, because it can be changed into a prime (209808041) 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, 8124 + ... + 22036.

Almost surely, 2^209808040 is an apocalyptic number.

209808040 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 209808040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (262974600).

209808040 is an abundant number, since it is smaller than the sum of its proper divisors (316141160).

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

209808040 is a wasteful number, since it uses less digits than its factorization.

209808040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13966 (or 13962 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 31.

The square root of 209808040 is about 14484.7519826886. The cubic root of 209808040 is about 594.2110297058.

The spelling of 209808040 in words is "two hundred nine million, eight hundred eight thousand, forty".