1221543563 has 8 divisors (see below), whose sum is σ = 1225753200. Its totient is φ = 1217341440.

The previous prime is 1221543559. The next prime is 1221543577. The reversal of 1221543563 is 3653451221.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221543563 - 2² = 1221543559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221543553) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 686531 + ... + 688307.

It is an arithmetic number, because the mean of its divisors is an integer number (153219150).

Almost surely, 2^1221543563 is an apocalyptic number.

1221543563 is a deficient number, since it is larger than the sum of its proper divisors (4209637).

1221543563 is a wasteful number, since it uses less digits than its factorization.

1221543563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3757.

The product of its digits is 21600, while the sum is 32.

The square root of 1221543563 is about 34950.5874485680. The cubic root of 1221543563 is about 1068.9801803819.

Adding to 1221543563 its reverse (3653451221), we get a palindrome (4874994784).

The spelling of 1221543563 in words is "one billion, two hundred twenty-one million, five hundred forty-three thousand, five hundred sixty-three".