21003443 has 4 divisors (see below), whose sum is σ = 21083568. Its totient is φ = 20923320.

The previous prime is 21003431. The next prime is 21003473. The reversal of 21003443 is 34430012.

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 21003443 - 2⁴ = 21003427 is a prime.

It is a super-2 number, since 2×21003443² = 882289235708498, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21003413) 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, 39668 + ... + 40193.

It is an arithmetic number, because the mean of its divisors is an integer number (5270892).

Almost surely, 2^21003443 is an apocalyptic number.

21003443 is a deficient number, since it is larger than the sum of its proper divisors (80125).

21003443 is an equidigital number, since it uses as much as digits as its factorization.

21003443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80124.

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 21003443 is about 4582.9513416575. The cubic root of 21003443 is about 275.9074945538.

Adding to 21003443 its reverse (34430012), we get a palindrome (55433455).

The spelling of 21003443 in words is "twenty-one million, three thousand, four hundred forty-three".