518421 has 4 divisors (see below), whose sum is σ = 691232. Its totient is φ = 345612.

The previous prime is 518417. The next prime is 518429. The reversal of 518421 is 124815.

518421 is digitally balanced in base 7, 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.

It is not a de Polignac number, because 518421 - 2² = 518417 is a prime.

It is a D-number.

It is a Duffinian number.

518421 is strictly pandigital in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (518429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86401 + ... + 86406.

It is an arithmetic number, because the mean of its divisors is an integer number (172808).

2⁵¹⁸⁴²¹ is an apocalyptic number.

It is an amenable number.

518421 is a deficient number, since it is larger than the sum of its proper divisors (172811).

518421 is a wasteful number, since it uses less digits than its factorization.

518421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172810.

The product of its digits is 320, while the sum is 21.

The square root of 518421 is about 720.0145831856. The cubic root of 518421 is about 80.3330387245. Note that the first 3 decimals are identical.

Subtracting from 518421 its sum of digits (21), we obtain a square (518400 = 720²).

It can be divided in two parts, 518 and 421, that added together give a palindrome (939).

The spelling of 518421 in words is "five hundred eighteen thousand, four hundred twenty-one".