1221043543 has 4 divisors (see below), whose sum is σ = 1221151680. Its totient is φ = 1220935408.

The previous prime is 1221043529. The next prime is 1221043601. The reversal of 1221043543 is 3453401221.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1221043543 - 2⁵ = 1221043511 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 (1221040543) 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, 34855 + ... + 60472.

It is an arithmetic number, because the mean of its divisors is an integer number (305287920).

Almost surely, 2^1221043543 is an apocalyptic number.

1221043543 is a deficient number, since it is larger than the sum of its proper divisors (108137).

1221043543 is an equidigital number, since it uses as much as digits as its factorization.

1221043543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108136.

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 1221043543 is about 34943.4334746888. The cubic root of 1221043543 is about 1068.8343036311.

Adding to 1221043543 its reverse (3453401221), we get a palindrome (4674444764).

The spelling of 1221043543 in words is "one billion, two hundred twenty-one million, forty-three thousand, five hundred forty-three".