821406 has 16 divisors (see below), whose sum is σ = 1739664. Its totient is φ = 257664.

The previous prime is 821383. The next prime is 821411. The reversal of 821406 is 604128.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3925 + ... + 4128.

It is an arithmetic number, because the mean of its divisors is an integer number (108729).

2⁸²¹⁴⁰⁶ is an apocalyptic number.

821406 is an abundant number, since it is smaller than the sum of its proper divisors (918258).

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

821406 is a wasteful number, since it uses less digits than its factorization.

821406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8075.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 821406 is about 906.3145149450. The cubic root of 821406 is about 93.6524817082.

The spelling of 821406 in words is "eight hundred twenty-one thousand, four hundred six".