871721 has 4 divisors (see below), whose sum is σ = 873600. Its totient is φ = 869844.

The previous prime is 871687. The next prime is 871727. The reversal of 871721 is 127178.

871721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 127178 = 2 ⋅63589.

It is a cyclic number.

It is not a de Polignac number, because 871721 - 2⁶ = 871657 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (871727) 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, 320 + ... + 1358.

It is an arithmetic number, because the mean of its divisors is an integer number (218400).

2⁸⁷¹⁷²¹ is an apocalyptic number.

It is an amenable number.

871721 is a deficient number, since it is larger than the sum of its proper divisors (1879).

871721 is a wasteful number, since it uses less digits than its factorization.

871721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1878.

The product of its digits is 784, while the sum is 26.

The square root of 871721 is about 933.6600023563. The cubic root of 871721 is about 95.5269333681.

Adding to 871721 its reverse (127178), we get a palindrome (998899).

The spelling of 871721 in words is "eight hundred seventy-one thousand, seven hundred twenty-one".