1820220 has 48 divisors (see below), whose sum is σ = 5322240. Its totient is φ = 463936.

The previous prime is 1820213. The next prime is 1820237. The reversal of 1820220 is 220281.

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 1820220.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 721 + ... + 2039.

It is an arithmetic number, because the mean of its divisors is an integer number (110880).

2^1820220 is an apocalyptic number.

1820220 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 1820220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2661120).

1820220 is an abundant number, since it is smaller than the sum of its proper divisors (3502020).

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

1820220 is a wasteful number, since it uses less digits than its factorization.

1820220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1354 (or 1352 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 1820220 is about 1349.1552912841. The cubic root of 1820220 is about 122.0978342712.

The spelling of 1820220 in words is "one million, eight hundred twenty thousand, two hundred twenty".