209820256 has 48 divisors (see below), whose sum is σ = 440971776. Its totient is φ = 97929216.

The previous prime is 209820253. The next prime is 209820271. The reversal of 209820256 is 652028902.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209820253) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 67570 + ... + 70606.

It is an arithmetic number, because the mean of its divisors is an integer number (9186912).

Almost surely, 2^209820256 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 209820256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (220485888).

209820256 is an abundant number, since it is smaller than the sum of its proper divisors (231151520).

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

209820256 is a wasteful number, since it uses less digits than its factorization.

209820256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3191 (or 3183 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 209820256 is about 14485.1736613684. The cubic root of 209820256 is about 594.2225620587. Note that the first 3 decimals are identical.

The spelling of 209820256 in words is "two hundred nine million, eight hundred twenty thousand, two hundred fifty-six".