521406 has 24 divisors (see below), whose sum is σ = 1146600. Its totient is φ = 171216.

The previous prime is 521401. The next prime is 521429. The reversal of 521406 is 604125.

521406 = T₆₈ + T₆₉ + ... + T₁₅₀.

It is a happy number.

521406 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nialpdrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521401) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1320 + ... + 1668.

It is an arithmetic number, because the mean of its divisors is an integer number (47775).

2⁵²¹⁴⁰⁶ is an apocalyptic number.

521406 is an abundant number, since it is smaller than the sum of its proper divisors (625194).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

521406 is a wasteful number, since it uses less digits than its factorization.

521406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 440 (or 437 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 521406 is about 722.0844825919. The cubic root of 521406 is about 80.4869261075.

The spelling of 521406 in words is "five hundred twenty-one thousand, four hundred six".