261889 has 4 divisors (see below), whose sum is σ = 262960. Its totient is φ = 260820.

The previous prime is 261887. The next prime is 261917. The reversal of 261889 is 988162.

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 261889 - 2¹ = 261887 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261881) 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, 34 + ... + 724.

It is an arithmetic number, because the mean of its divisors is an integer number (65740).

261889 is a Friedman number, since it can be written as 8^6-2^8+1^9, using all its digits and the basic arithmetic operations.

2²⁶¹⁸⁸⁹ is an apocalyptic number.

It is an amenable number.

261889 is a deficient number, since it is larger than the sum of its proper divisors (1071).

261889 is an equidigital number, since it uses as much as digits as its factorization.

261889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1070.

The product of its digits is 6912, while the sum is 34.

The square root of 261889 is about 511.7509159738. The cubic root of 261889 is about 63.9792413144.

The spelling of 261889 in words is "two hundred sixty-one thousand, eight hundred eighty-nine".