1801221 has 4 divisors (see below), whose sum is σ = 2401632. Its totient is φ = 1200812.

The previous prime is 1801213. The next prime is 1801223. The reversal of 1801221 is 1221081.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1801221 - 2³ = 1801213 is a prime.

It is a D-number.

1801221 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1801221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1801223) 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, 300201 + ... + 300206.

It is an arithmetic number, because the mean of its divisors is an integer number (600408).

2^1801221 is an apocalyptic number.

It is an amenable number.

1801221 is a deficient number, since it is larger than the sum of its proper divisors (600411).

1801221 is an equidigital number, since it uses as much as digits as its factorization.

1801221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 600410.

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

The square root of 1801221 is about 1342.0957491923. The cubic root of 1801221 is about 121.6715387636.

The spelling of 1801221 in words is "one million, eight hundred one thousand, two hundred twenty-one".