1604221 has 4 divisors (see below), whose sum is σ = 1607452. Its totient is φ = 1600992.

The previous prime is 1604191. The next prime is 1604231. The reversal of 1604221 is 1224061.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1224061 = 29 ⋅42209.

It can be written as a sum of positive squares in 2 ways, for example, as 722500 + 881721 = 850^2 + 939^2 .

It is a cyclic number.

It is not a de Polignac number, because 1604221 - 2⁷ = 1604093 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1604195 and 1604204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1604231) 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 3 ways as a sum of consecutive naturals, for example, 696 + ... + 1921.

It is an arithmetic number, because the mean of its divisors is an integer number (401863).

2^1604221 is an apocalyptic number.

It is an amenable number.

1604221 is a deficient number, since it is larger than the sum of its proper divisors (3231).

1604221 is an equidigital number, since it uses as much as digits as its factorization.

1604221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3230.

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 1604221 is about 1266.5784618412. The cubic root of 1604221 is about 117.0634715390.

Adding to 1604221 its reverse (1224061), we get a palindrome (2828282).

The spelling of 1604221 in words is "one million, six hundred four thousand, two hundred twenty-one".