261288720 has 320 divisors, whose sum is σ = 1122785280. Its totient is φ = 54259200.

The previous prime is 261288719. The next prime is 261288721. The reversal of 261288720 is 27882162.

It is a happy number.

261288720 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (261288719) and next prime (261288721).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (261288721) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 165535 + ... + 167105.

It is an arithmetic number, because the mean of its divisors is an integer number (3508704).

Almost surely, 2^261288720 is an apocalyptic number.

261288720 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 261288720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (561392640).

261288720 is an abundant number, since it is smaller than the sum of its proper divisors (861496560).

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

261288720 is a wasteful number, since it uses less digits than its factorization.

261288720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1611 (or 1599 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 261288720 is about 16164.4276112704. The cubic root of 261288720 is about 639.3032130168.

The spelling of 261288720 in words is "two hundred sixty-one million, two hundred eighty-eight thousand, seven hundred twenty".