261116720 has 80 divisors (see below), whose sum is σ = 630912000. Its totient is φ = 100396800.

The previous prime is 261116717. The next prime is 261116731. The reversal of 261116720 is 27611162.

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 261116720.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 523031 + ... + 523529.

It is an arithmetic number, because the mean of its divisors is an integer number (7886400).

Almost surely, 2^261116720 is an apocalyptic number.

261116720 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 261116720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (315456000).

261116720 is an abundant number, since it is smaller than the sum of its proper divisors (369795280).

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

261116720 is a wasteful number, since it uses less digits than its factorization.

261116720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 754 (or 748 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 261116720 is about 16159.1064109375. The cubic root of 261116720 is about 639.1629029803.

Adding to 261116720 its reverse (27611162), we get a palindrome (288727882).

The spelling of 261116720 in words is "two hundred sixty-one million, one hundred sixteen thousand, seven hundred twenty".