1800020 has 12 divisors (see below), whose sum is σ = 3780084. Its totient is φ = 720000.

The previous prime is 1800017. The next prime is 1800037. The reversal of 1800020 is 200081.

It can be written as a sum of positive squares in 2 ways, for example, as 1435204 + 364816 = 1198^2 + 604^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1799974 and 1800010.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44981 + ... + 45020.

It is an arithmetic number, because the mean of its divisors is an integer number (315007).

2^1800020 is an apocalyptic number.

1800020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1800020 is an abundant number, since it is smaller than the sum of its proper divisors (1980064).

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

1800020 is a wasteful number, since it uses less digits than its factorization.

1800020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90010 (or 90008 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 1800020 is about 1341.6482400391. The cubic root of 1800020 is about 121.6444904433.

It can be divided in two parts, 18000 and 20, that multiplied together give a square (360000 = 600²).

The spelling of 1800020 in words is "one million, eight hundred thousand, twenty".