521391 has 16 divisors (see below), whose sum is σ = 776160. Its totient is φ = 309120.

The previous prime is 521377. The next prime is 521393. The reversal of 521391 is 193125.

It is not a de Polignac number, because 521391 - 2⁵ = 521359 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521393) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 901 + ... + 1361.

It is an arithmetic number, because the mean of its divisors is an integer number (48510).

2⁵²¹³⁹¹ is an apocalyptic number.

521391 is a deficient number, since it is larger than the sum of its proper divisors (254769).

521391 is a wasteful number, since it uses less digits than its factorization.

521391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 506.

The product of its digits is 270, while the sum is 21.

The square root of 521391 is about 722.0740959209. The cubic root of 521391 is about 80.4861542742.

The spelling of 521391 in words is "five hundred twenty-one thousand, three hundred ninety-one".