1812820 has 12 divisors (see below), whose sum is σ = 3806964. Its totient is φ = 725120.

The previous prime is 1812817. The next prime is 1812821. The reversal of 1812820 is 282181.

It can be written as a sum of positive squares in 2 ways, for example, as 1153476 + 659344 = 1074^2 + 812^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1812791 and 1812800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1812821) 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 3 ways as a sum of consecutive naturals, for example, 45301 + ... + 45340.

It is an arithmetic number, because the mean of its divisors is an integer number (317247).

2^1812820 is an apocalyptic number.

1812820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1812820 is an abundant number, since it is smaller than the sum of its proper divisors (1994144).

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

1812820 is a wasteful number, since it uses less digits than its factorization.

1812820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90650 (or 90648 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 22.

The square root of 1812820 is about 1346.4100415549. The cubic root of 1812820 is about 121.9321489594.

The spelling of 1812820 in words is "one million, eight hundred twelve thousand, eight hundred twenty".