1553345221 has 4 divisors (see below), whose sum is σ = 1557954892. Its totient is φ = 1548735552.

The previous prime is 1553345203. The next prime is 1553345231. The reversal of 1553345221 is 1225433551.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1225433551 = 67 ⋅18290053.

It can be written as a sum of positive squares in 2 ways, for example, as 713157025 + 840188196 = 26705^2 + 28986^2 .

It is a cyclic number.

It is not a de Polignac number, because 1553345221 - 2²³ = 1544956613 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 (1553345231) 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, 2304330 + ... + 2305003.

It is an arithmetic number, because the mean of its divisors is an integer number (389488723).

Almost surely, 2^1553345221 is an apocalyptic number.

It is an amenable number.

1553345221 is a deficient number, since it is larger than the sum of its proper divisors (4609671).

1553345221 is an equidigital number, since it uses as much as digits as its factorization.

1553345221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4609670.

The product of its digits is 18000, while the sum is 31.

The square root of 1553345221 is about 39412.5008214399. The cubic root of 1553345221 is about 1158.1264894547.

Adding to 1553345221 its reverse (1225433551), we get a palindrome (2778778772).

The spelling of 1553345221 in words is "one billion, five hundred fifty-three million, three hundred forty-five thousand, two hundred twenty-one".