820491 has 16 divisors (see below), whose sum is σ = 1267200. Its totient is φ = 462528.

The previous prime is 820489. The next prime is 820537. The reversal of 820491 is 194028.

It is not a de Polignac number, because 820491 - 2¹ = 820489 is a prime.

820491 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (820411) 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, 1650 + ... + 2088.

It is an arithmetic number, because the mean of its divisors is an integer number (79200).

2⁸²⁰⁴⁹¹ is an apocalyptic number.

820491 is a deficient number, since it is larger than the sum of its proper divisors (446709).

820491 is a wasteful number, since it uses less digits than its factorization.

820491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 538.

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 820491 is about 905.8095826386. The cubic root of 820491 is about 93.6176942588.

The spelling of 820491 in words is "eight hundred twenty thousand, four hundred ninety-one".