1553213221 has 12 divisors (see below), whose sum is σ = 1811538432. Its totient is φ = 1327833528.

The previous prime is 1553213219. The next prime is 1553213237. The reversal of 1553213221 is 1223123551.

It is not a de Polignac number, because 1553213221 - 2¹ = 1553213219 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 (1553213261) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22615 + ... + 60148.

It is an arithmetic number, because the mean of its divisors is an integer number (150961536).

Almost surely, 2^1553213221 is an apocalyptic number.

It is an amenable number.

1553213221 is a deficient number, since it is larger than the sum of its proper divisors (258325211).

1553213221 is an equidigital number, since it uses as much as digits as its factorization.

1553213221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83160 (or 83153 counting only the distinct ones).

The product of its digits is 1800, while the sum is 25.

The square root of 1553213221 is about 39410.8261902742. The cubic root of 1553213221 is about 1158.0936834768.

Adding to 1553213221 its reverse (1223123551), we get a palindrome (2776336772).

The spelling of 1553213221 in words is "one billion, five hundred fifty-three million, two hundred thirteen thousand, two hundred twenty-one".