521891 has 8 divisors (see below), whose sum is σ = 546480. Its totient is φ = 497952.

The previous prime is 521887. The next prime is 521897. The reversal of 521891 is 198125.

521891 = T₁₁₃ + T₁₁₄ + ... + T₁₆₅.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 521891 - 2² = 521887 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a zygodrome in base 3.

It is a self number, because there is not a number n which added to its sum of digits gives 521891.

It is not an unprimeable number, because it can be changed into a prime (521897) 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 7 ways as a sum of consecutive naturals, for example, 2165 + ... + 2393.

It is an arithmetic number, because the mean of its divisors is an integer number (68310).

2⁵²¹⁸⁹¹ is an apocalyptic number.

521891 is a deficient number, since it is larger than the sum of its proper divisors (24589).

521891 is a wasteful number, since it uses less digits than its factorization.

521891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 325.

The product of its digits is 720, while the sum is 26.

The square root of 521891 is about 722.4202378118. The cubic root of 521891 is about 80.5118740763.

The spelling of 521891 in words is "five hundred twenty-one thousand, eight hundred ninety-one".