871561 has 4 divisors (see below), whose sum is σ = 877072. Its totient is φ = 866052.

The previous prime is 871553. The next prime is 871571. The reversal of 871561 is 165178.

It is a happy number.

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 a cyclic number.

It is not a de Polignac number, because 871561 - 2³ = 871553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (871531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2511 + ... + 2836.

It is an arithmetic number, because the mean of its divisors is an integer number (219268).

2⁸⁷¹⁵⁶¹ is an apocalyptic number.

It is an amenable number.

871561 is a deficient number, since it is larger than the sum of its proper divisors (5511).

871561 is a wasteful number, since it uses less digits than its factorization.

871561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5510.

The product of its digits is 1680, while the sum is 28.

The square root of 871561 is about 933.5743141282. The cubic root of 871561 is about 95.5210885146.

The spelling of 871561 in words is "eight hundred seventy-one thousand, five hundred sixty-one".