261785856 has 72 divisors (see below), whose sum is σ = 737753184. Its totient is φ = 82124800.

The previous prime is 261785851. The next prime is 261785869. The reversal of 261785856 is 658587162.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is not an unprimeable number, because it can be changed into a prime (261785851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3031 + ... + 23081.

It is an arithmetic number, because the mean of its divisors is an integer number (10246572).

Almost surely, 2^261785856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261785856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (368876592).

261785856 is an abundant number, since it is smaller than the sum of its proper divisors (475967328).

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

261785856 is a wasteful number, since it uses less digits than its factorization.

261785856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20087 (or 20073 counting only the distinct ones).

The product of its digits is 806400, while the sum is 48.

The square root of 261785856 is about 16179.7977737671. The cubic root of 261785856 is about 639.7084088346.

The spelling of 261785856 in words is "two hundred sixty-one million, seven hundred eighty-five thousand, eight hundred fifty-six".