1808820 has 72 divisors (see below), whose sum is σ = 5916456. Its totient is φ = 444672.

The previous prime is 1808813. The next prime is 1808831. The reversal of 1808820 is 288081.

It can be written as a sum of positive squares in 4 ways, for example, as 34596 + 1774224 = 186^2 + 1332^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1954 + ... + 2726.

It is an arithmetic number, because the mean of its divisors is an integer number (82173).

2^1808820 is an apocalyptic number.

1808820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1808820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2958228).

1808820 is an abundant number, since it is smaller than the sum of its proper divisors (4107636).

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

1808820 is a wasteful number, since it uses less digits than its factorization.

1808820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 801 (or 796 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 27.

The square root of 1808820 is about 1344.9237896624. The cubic root of 1808820 is about 121.8424015379.

It can be divided in two parts, 1808 and 820, that added together give a triangular number (2628 = T₇₂).

The spelling of 1808820 in words is "one million, eight hundred eight thousand, eight hundred twenty".