261840320 has 84 divisors (see below), whose sum is σ = 725347800. Its totient is φ = 89768448.

The previous prime is 261840259. The next prime is 261840343. The reversal of 261840320 is 23048162.

It is a self number, because there is not a number n which added to its sum of digits gives 261840320.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7331 + ... + 24029.

Almost surely, 2^261840320 is an apocalyptic number.

261840320 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 261840320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (362673900).

261840320 is an abundant number, since it is smaller than the sum of its proper divisors (463507480).

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

261840320 is a wasteful number, since it uses less digits than its factorization.

261840320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16730 (or 16713 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 261840320 is about 16181.4807727847. The cubic root of 261840320 is about 639.7527690908.

Adding to 261840320 its reverse (23048162), we get a palindrome (284888482).

The spelling of 261840320 in words is "two hundred sixty-one million, eight hundred forty thousand, three hundred twenty".