261571 has 4 divisors (see below), whose sum is σ = 264600. Its totient is φ = 258544.

The previous prime is 261563. The next prime is 261577. The reversal of 261571 is 175162.

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 261571 - 2³ = 261563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261577) 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, 1381 + ... + 1558.

It is an arithmetic number, because the mean of its divisors is an integer number (66150).

2²⁶¹⁵⁷¹ is an apocalyptic number.

261571 is a deficient number, since it is larger than the sum of its proper divisors (3029).

261571 is an equidigital number, since it uses as much as digits as its factorization.

261571 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3028.

The product of its digits is 420, while the sum is 22.

The square root of 261571 is about 511.4401235726. The cubic root of 261571 is about 63.9533351237.

The spelling of 261571 in words is "two hundred sixty-one thousand, five hundred seventy-one".