521687 has 4 divisors (see below), whose sum is σ = 524160. Its totient is φ = 519216.

The previous prime is 521671. The next prime is 521693. The reversal of 521687 is 786125.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 521687 - 2⁴ = 521671 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521657) 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, 887 + ... + 1352.

It is an arithmetic number, because the mean of its divisors is an integer number (131040).

2⁵²¹⁶⁸⁷ is an apocalyptic number.

521687 is a deficient number, since it is larger than the sum of its proper divisors (2473).

521687 is a wasteful number, since it uses less digits than its factorization.

521687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2472.

The product of its digits is 3360, while the sum is 29.

The square root of 521687 is about 722.2790319537. The cubic root of 521687 is about 80.5013823818.

The spelling of 521687 in words is "five hundred twenty-one thousand, six hundred eighty-seven".