261589 has 4 divisors (see below), whose sum is σ = 262656.
Its totient is φ = 260524.
The previous prime is 261587. The next prime is 261593. The reversal of 261589 is 985162.
It can be divided in two parts, 2615 and 89, that added together give a square (2704 = 522).
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.
It is a cyclic number.
It is not a de Polignac number, because 261589 - 21 = 261587 is a prime.
It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.
It is a Duffinian number.
261589 is a lucky number.
It is a self number, because there is not a number n which added to its sum of digits gives 261589.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (261581) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42 + ... + 724.
It is an arithmetic number, because the mean of its divisors is an integer number (65664).
2261589 is an apocalyptic number.
It is an amenable number.
261589 is a deficient number, since it is larger than the sum of its proper divisors (1067).
261589 is an equidigital number, since it uses as much as digits as its factorization.
261589 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1066.
The product of its digits is 4320, while the sum is 31.
The square root of 261589 is about 511.4577206378.
The cubic root of 261589 is about 63.9548020723.
The spelling of 261589 in words is "two hundred sixty-one thousand, five hundred eighty-nine".