261771 has 4 divisors (see below), whose sum is σ = 349032. Its totient is φ = 174512.

The previous prime is 261761. The next prime is 261773. The reversal of 261771 is 177162.

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 261771 - 2⁵ = 261739 is a prime.

It is a D-number.

It is not an unprimeable number, because it can be changed into a prime (261773) by changing a digit.

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, 43626 + ... + 43631.

It is an arithmetic number, because the mean of its divisors is an integer number (87258).

2²⁶¹⁷⁷¹ is an apocalyptic number.

261771 is a deficient number, since it is larger than the sum of its proper divisors (87261).

261771 is an equidigital number, since it uses as much as digits as its factorization.

261771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87260.

The product of its digits is 588, while the sum is 24.

The square root of 261771 is about 511.6356125213. The cubic root of 261771 is about 63.9696307738.

The spelling of 261771 in words is "two hundred sixty-one thousand, seven hundred seventy-one".