261566 has 4 divisors (see below), whose sum is σ = 392352. Its totient is φ = 130782.

The previous prime is 261563. The next prime is 261577. The reversal of 261566 is 665162.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65390 + ... + 65393.

It is an arithmetic number, because the mean of its divisors is an integer number (98088).

2²⁶¹⁵⁶⁶ is an apocalyptic number.

261566 is a deficient number, since it is larger than the sum of its proper divisors (130786).

261566 is a wasteful number, since it uses less digits than its factorization.

261566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130785.

The product of its digits is 2160, while the sum is 26.

The square root of 261566 is about 511.4352353915. The cubic root of 261566 is about 63.9529276261.

It can be divided in two parts, 26156 and 6, that added together give a palindrome (26162).

The spelling of 261566 in words is "two hundred sixty-one thousand, five hundred sixty-six".