261366656 has 32 divisors (see below), whose sum is σ = 526564800. Its totient is φ = 129209344.

The previous prime is 261366629. The next prime is 261366659. The reversal of 261366656 is 656663162.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261366659) 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 3 ways as a sum of consecutive naturals, for example, 80 + ... + 22863.

It is an arithmetic number, because the mean of its divisors is an integer number (16455150).

Almost surely, 2^261366656 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 261366656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (263282400).

261366656 is an abundant number, since it is smaller than the sum of its proper divisors (265198144).

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

261366656 is an equidigital number, since it uses as much as digits as its factorization.

261366656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23046 (or 23034 counting only the distinct ones).

The product of its digits is 233280, while the sum is 41.

The square root of 261366656 is about 16166.8381571660. The cubic root of 261366656 is about 639.3667695074.

The spelling of 261366656 in words is "two hundred sixty-one million, three hundred sixty-six thousand, six hundred fifty-six".