321220021553 has 4 divisors (see below), whose sum is σ = 324400417908. Its totient is φ = 318039625200.

The previous prime is 321220021531. The next prime is 321220021583. The reversal of 321220021553 is 355120022123.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 355120022123 = 101 ⋅3516039823.

It can be written as a sum of positive squares in 2 ways, for example, as 237994695409 + 83225326144 = 487847^2 + 288488^2 .

It is a cyclic number.

It is not a de Polignac number, because 321220021553 - 2²⁴ = 321203244337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (321220021583) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1590198026 + ... + 1590198227.

It is an arithmetic number, because the mean of its divisors is an integer number (81100104477).

Almost surely, 2^321220021553 is an apocalyptic number.

It is an amenable number.

321220021553 is a deficient number, since it is larger than the sum of its proper divisors (3180396355).

321220021553 is a wasteful number, since it uses less digits than its factorization.

321220021553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3180396354.

The product of its (nonzero) digits is 3600, while the sum is 26.

Adding to 321220021553 its reverse (355120022123), we get a palindrome (676340043676).

The spelling of 321220021553 in words is "three hundred twenty-one billion, two hundred twenty million, twenty-one thousand, five hundred fifty-three".