1553221 has 4 divisors (see below), whose sum is σ = 1574572. Its totient is φ = 1531872.

The previous prime is 1553191. The next prime is 1553249. The reversal of 1553221 is 1223551.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 408321 + 1144900 = 639^2 + 1070^2 .

It is a cyclic number.

It is not a de Polignac number, because 1553221 - 2⁷ = 1553093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1553281) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10566 + ... + 10711.

It is an arithmetic number, because the mean of its divisors is an integer number (393643).

2^1553221 is an apocalyptic number.

It is an amenable number.

1553221 is a deficient number, since it is larger than the sum of its proper divisors (21351).

1553221 is an equidigital number, since it uses as much as digits as its factorization.

1553221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21350.

The product of its digits is 300, while the sum is 19.

The square root of 1553221 is about 1246.2828731873. The cubic root of 1553221 is about 115.8095616844.

Adding to 1553221 its reverse (1223551), we get a palindrome (2776772).

The spelling of 1553221 in words is "one million, five hundred fifty-three thousand, two hundred twenty-one".