261306720 has 144 divisors (see below), whose sum is σ = 903389760. Its totient is φ = 68769792.

The previous prime is 261306713. The next prime is 261306739. The reversal of 261306720 is 27603162.

It is a happy number.

261306720 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (144).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 112612 + ... + 114908.

It is an arithmetic number, because the mean of its divisors is an integer number (6273540).

Almost surely, 2^261306720 is an apocalyptic number.

261306720 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 261306720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (451694880).

261306720 is an abundant number, since it is smaller than the sum of its proper divisors (642083040).

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

261306720 is a wasteful number, since it uses less digits than its factorization.

261306720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2397 (or 2386 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 27.

The square root of 261306720 is about 16164.9843798254. The cubic root of 261306720 is about 639.3178930658.

Adding to 261306720 its reverse (27603162), we get a palindrome (288909882).

The spelling of 261306720 in words is "two hundred sixty-one million, three hundred six thousand, seven hundred twenty".