261330240 has 112 divisors (see below), whose sum is σ = 836200512. Its totient is φ = 69144576.

The previous prime is 261330203. The next prime is 261330247. The reversal of 261330240 is 42033162.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261330247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 130527 + ... + 132513.

It is an arithmetic number, because the mean of its divisors is an integer number (7466076).

Almost surely, 2^261330240 is an apocalyptic number.

261330240 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 261330240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (418100256).

261330240 is an abundant number, since it is smaller than the sum of its proper divisors (574870272).

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

261330240 is a wasteful number, since it uses less digits than its factorization.

261330240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2144 (or 2134 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 21.

The square root of 261330240 is about 16165.7118618389. The cubic root of 261330240 is about 639.3370739805.

The spelling of 261330240 in words is "two hundred sixty-one million, three hundred thirty thousand, two hundred forty".