21203443 has 4 divisors (see below), whose sum is σ = 21398080. Its totient is φ = 21008808.

The previous prime is 21203431. The next prime is 21203459. The reversal of 21203443 is 34430212.

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 21203443 - 2²¹ = 19106291 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21203443.

It is not an unprimeable number, because it can be changed into a prime (21203543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 97155 + ... + 97372.

It is an arithmetic number, because the mean of its divisors is an integer number (5349520).

Almost surely, 2^21203443 is an apocalyptic number.

21203443 is a deficient number, since it is larger than the sum of its proper divisors (194637).

21203443 is a wasteful number, since it uses less digits than its factorization.

21203443 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194636.

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 21203443 is about 4604.7196440174. The cubic root of 21203443 is about 276.7804826792.

Adding to 21203443 its reverse (34430212), we get a palindrome (55633655).

The spelling of 21203443 in words is "twenty-one million, two hundred three thousand, four hundred forty-three".