1811220 has 24 divisors (see below), whose sum is σ = 5071584. Its totient is φ = 482976.

The previous prime is 1811219. The next prime is 1811287. The reversal of 1811220 is 221181.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 1811220.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15034 + ... + 15153.

It is an arithmetic number, because the mean of its divisors is an integer number (211316).

2^1811220 is an apocalyptic number.

1811220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1811220 is an abundant number, since it is smaller than the sum of its proper divisors (3260364).

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

1811220 is a wasteful number, since it uses less digits than its factorization.

1811220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30199 (or 30197 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

The square root of 1811220 is about 1345.8157377591. The cubic root of 1811220 is about 121.8962658486.

The spelling of 1811220 in words is "one million, eight hundred eleven thousand, two hundred twenty".