820605 has 16 divisors (see below), whose sum is σ = 1324224. Its totient is φ = 433920.

The previous prime is 820597. The next prime is 820609. The reversal of 820605 is 506028.

It is a happy number.

It is not a de Polignac number, because 820605 - 2³ = 820597 is a prime.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820609) 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 15 ways as a sum of consecutive naturals, for example, 3285 + ... + 3525.

It is an arithmetic number, because the mean of its divisors is an integer number (82764).

2⁸²⁰⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

820605 is a deficient number, since it is larger than the sum of its proper divisors (503619).

820605 is a wasteful number, since it uses less digits than its factorization.

820605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 476.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 820605 is about 905.8725075859. The cubic root of 820605 is about 93.6220298427.

The spelling of 820605 in words is "eight hundred twenty thousand, six hundred five".