261240720 has 320 divisors, whose sum is σ = 937273344. Its totient is φ = 59719680.

The previous prime is 261240719. The next prime is 261240767. The reversal of 261240720 is 27042162.

261240720 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×261240720² = 136493427572236800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3578604 + ... + 3578676.

Almost surely, 2^261240720 is an apocalyptic number.

261240720 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 261240720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (468636672).

261240720 is an abundant number, since it is smaller than the sum of its proper divisors (676032624).

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

261240720 is a wasteful number, since it uses less digits than its factorization.

261240720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170 (or 164 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 24.

The square root of 261240720 is about 16162.9428013589. The cubic root of 261240720 is about 639.2640629233.

Adding to 261240720 its reverse (27042162), we get a palindrome (288282882).

The spelling of 261240720 in words is "two hundred sixty-one million, two hundred forty thousand, seven hundred twenty".