871581 has 4 divisors (see below), whose sum is σ = 1162112. Its totient is φ = 581052.

The previous prime is 871571. The next prime is 871589. The reversal of 871581 is 185178.

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.

It is not a de Polignac number, because 871581 - 2⁶ = 871517 is a prime.

It is a super-2 number, since 2×871581² = 1519306879122, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (871589) 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, 145261 + ... + 145266.

It is an arithmetic number, because the mean of its divisors is an integer number (290528).

2⁸⁷¹⁵⁸¹ is an apocalyptic number.

It is an amenable number.

871581 is a deficient number, since it is larger than the sum of its proper divisors (290531).

871581 is a wasteful number, since it uses less digits than its factorization.

871581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290530.

The product of its digits is 2240, while the sum is 30.

The square root of 871581 is about 933.5850255869. The cubic root of 871581 is about 95.5218191604.

The spelling of 871581 in words is "eight hundred seventy-one thousand, five hundred eighty-one".