261309280 has 96 divisors (see below), whose sum is σ = 665280000. Its totient is φ = 96671232.

The previous prime is 261309247. The next prime is 261309283. The reversal of 261309280 is 82903162.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261309283) 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, 129721 + ... + 131719.

It is an arithmetic number, because the mean of its divisors is an integer number (6930000).

Almost surely, 2^261309280 is an apocalyptic number.

261309280 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 261309280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (332640000).

261309280 is an abundant number, since it is smaller than the sum of its proper divisors (403970720).

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

261309280 is a wasteful number, since it uses less digits than its factorization.

261309280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2076 (or 2068 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 261309280 is about 16165.0635631290. The cubic root of 261309280 is about 639.3199808402.

The spelling of 261309280 in words is "two hundred sixty-one million, three hundred nine thousand, two hundred eighty".