261591 has 8 divisors (see below), whose sum is σ = 380544. Its totient is φ = 158520.

The previous prime is 261587. The next prime is 261593. The reversal of 261591 is 195162.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 261591 - 2² = 261587 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261593) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3931 + ... + 3996.

It is an arithmetic number, because the mean of its divisors is an integer number (47568).

2²⁶¹⁵⁹¹ is an apocalyptic number.

261591 is a deficient number, since it is larger than the sum of its proper divisors (118953).

261591 is a wasteful number, since it uses less digits than its factorization.

261591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7941.

The product of its digits is 540, while the sum is 24.

The square root of 261591 is about 511.4596758299. The cubic root of 261591 is about 63.9549650624.

The spelling of 261591 in words is "two hundred sixty-one thousand, five hundred ninety-one".