1321091553 has 4 divisors (see below), whose sum is σ = 1761455408. Its totient is φ = 880727700.

The previous prime is 1321091509. The next prime is 1321091581. The reversal of 1321091553 is 3551901231.

1321091553 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 3551901231 = 3 ⋅1183967077.

It is not a de Polignac number, because 1321091553 - 2¹⁴ = 1321075169 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1321091553.

It is not an unprimeable number, because it can be changed into a prime (1321091953) 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, 220181923 + ... + 220181928.

It is an arithmetic number, because the mean of its divisors is an integer number (440363852).

Almost surely, 2^1321091553 is an apocalyptic number.

It is an amenable number.

1321091553 is a deficient number, since it is larger than the sum of its proper divisors (440363855).

1321091553 is an equidigital number, since it uses as much as digits as its factorization.

1321091553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 440363854.

The product of its (nonzero) digits is 4050, while the sum is 30.

The square root of 1321091553 is about 36346.8231486605. The cubic root of 1321091553 is about 1097.2635987457.

Adding to 1321091553 its reverse (3551901231), we get a palindrome (4872992784).

The spelling of 1321091553 in words is "one billion, three hundred twenty-one million, ninety-one thousand, five hundred fifty-three".