261356566 has 16 divisors (see below), whose sum is σ = 402128064. Its totient is φ = 127338304.

The previous prime is 261356561. The next prime is 261356573. The reversal of 261356566 is 665653162.

It is a happy number.

261356566 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261356561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15936 + ... + 27868.

It is an arithmetic number, because the mean of its divisors is an integer number (25133004).

Almost surely, 2^261356566 is an apocalyptic number.

261356566 is a deficient number, since it is larger than the sum of its proper divisors (140771498).

261356566 is a wasteful number, since it uses less digits than its factorization.

261356566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12215.

The product of its digits is 194400, while the sum is 40.

The square root of 261356566 is about 16166.5260956088. The cubic root of 261356566 is about 639.3585418655.

The spelling of 261356566 in words is "two hundred sixty-one million, three hundred fifty-six thousand, five hundred sixty-six".