1563616321 has 4 divisors (see below), whose sum is σ = 1563697152. Its totient is φ = 1563535492.

The previous prime is 1563616279. The next prime is 1563616349. The reversal of 1563616321 is 1236163651.

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 a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1236163651 = 191 ⋅6472061.

It is a cyclic number.

It is not a de Polignac number, because 1563616321 - 2¹⁹ = 1563092033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1563616121) 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, 7680 + ... + 56446.

It is an arithmetic number, because the mean of its divisors is an integer number (390924288).

Almost surely, 2^1563616321 is an apocalyptic number.

It is an amenable number.

1563616321 is a deficient number, since it is larger than the sum of its proper divisors (80831).

1563616321 is an equidigital number, since it uses as much as digits as its factorization.

1563616321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80830.

The product of its digits is 19440, while the sum is 34.

The square root of 1563616321 is about 39542.5886987688. The cubic root of 1563616321 is about 1160.6734894491.

Adding to 1563616321 its reverse (1236163651), we get a palindrome (2799779972).

The spelling of 1563616321 in words is "one billion, five hundred sixty-three million, six hundred sixteen thousand, three hundred twenty-one".