21203220443 has 4 divisors (see below), whose sum is σ = 21887195328. Its totient is φ = 20519245560.

The previous prime is 21203220391. The next prime is 21203220461. The reversal of 21203220443 is 34402230212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21203220443 - 2⁸ = 21203220187 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21203220343) 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, 341987396 + ... + 341987457.

It is an arithmetic number, because the mean of its divisors is an integer number (5471798832).

Almost surely, 2^21203220443 is an apocalyptic number.

21203220443 is a deficient number, since it is larger than the sum of its proper divisors (683974885).

21203220443 is an equidigital number, since it uses as much as digits as its factorization.

21203220443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 683974884.

The product of its (nonzero) digits is 2304, while the sum is 23.

Adding to 21203220443 its reverse (34402230212), we get a palindrome (55605450655).

The spelling of 21203220443 in words is "twenty-one billion, two hundred three million, two hundred twenty thousand, four hundred forty-three".