820904 has 32 divisors (see below), whose sum is σ = 1788480. Its totient is φ = 345984.

The previous prime is 820901. The next prime is 820907. The reversal of 820904 is 409028.

It is an interprime number because it is at equal distance from previous prime (820901) and next prime (820907).

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 820904.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5924 + ... + 6060.

It is an arithmetic number, because the mean of its divisors is an integer number (55890).

2⁸²⁰⁹⁰⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 820904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (894240).

820904 is an abundant number, since it is smaller than the sum of its proper divisors (967576).

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

820904 is a wasteful number, since it uses less digits than its factorization.

820904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 257 (or 253 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 820904 is about 906.0375268166. The cubic root of 820904 is about 93.6333993355.

The spelling of 820904 in words is "eight hundred twenty thousand, nine hundred four".