261895 has 4 divisors (see below), whose sum is σ = 314280. Its totient is φ = 209512.

The previous prime is 261887. The next prime is 261917. The reversal of 261895 is 598162.

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

It is a cyclic number.

It is not a de Polignac number, because 261895 - 2³ = 261887 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.

261895 is a lucky number.

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26185 + ... + 26194.

It is an arithmetic number, because the mean of its divisors is an integer number (78570).

2²⁶¹⁸⁹⁵ is an apocalyptic number.

261895 is a deficient number, since it is larger than the sum of its proper divisors (52385).

261895 is an equidigital number, since it uses as much as digits as its factorization.

261895 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52384.

The product of its digits is 4320, while the sum is 31.

The square root of 261895 is about 511.7567781671. The cubic root of 261895 is about 63.9797299089.

It can be divided in two parts, 261 and 895, that added together give a square (1156 = 34²).

The spelling of 261895 in words is "two hundred sixty-one thousand, eight hundred ninety-five".