1820221 has 8 divisors (see below), whose sum is σ = 1974560. Its totient is φ = 1667952.

The previous prime is 1820213. The next prime is 1820237. The reversal of 1820221 is 1220281.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1820221 - 2³ = 1820213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1820195 and 1820204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1820201) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 1690 + ... + 2548.

It is an arithmetic number, because the mean of its divisors is an integer number (246820).

2^1820221 is an apocalyptic number.

It is an amenable number.

1820221 is a deficient number, since it is larger than the sum of its proper divisors (154339).

1820221 is a wasteful number, since it uses less digits than its factorization.

1820221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1035.

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 1820221 is about 1349.1556618864. The cubic root of 1820221 is about 122.0978566307.

The spelling of 1820221 in words is "one million, eight hundred twenty thousand, two hundred twenty-one".