209896640 has 28 divisors (see below), whose sum is σ = 499817136. Its totient is φ = 83958528.

The previous prime is 209896619. The next prime is 209896649. The reversal of 209896640 is 46698902.

It is a junction number, because it is equal to n+sod(n) for n = 209896591 and 209896600.

It is not an unprimeable number, because it can be changed into a prime (209896649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 327644 + ... + 328283.

It is an arithmetic number, because the mean of its divisors is an integer number (17850612).

Almost surely, 2^209896640 is an apocalyptic number.

209896640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

209896640 is an abundant number, since it is smaller than the sum of its proper divisors (289920496).

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

209896640 is an equidigital number, since it uses as much as digits as its factorization.

209896640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 655944 (or 655934 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 44.

The square root of 209896640 is about 14487.8100484511. The cubic root of 209896640 is about 594.2946612136.

The spelling of 209896640 in words is "two hundred nine million, eight hundred ninety-six thousand, six hundred forty".