21043003 has 4 divisors (see below), whose sum is σ = 21247408. Its totient is φ = 20838600.

The previous prime is 21042997. The next prime is 21043007. The reversal of 21043003 is 30034012.

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 21043003 - 2⁵ = 21042971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21043007) 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, 102048 + ... + 102253.

It is an arithmetic number, because the mean of its divisors is an integer number (5311852).

Almost surely, 2^21043003 is an apocalyptic number.

21043003 is a deficient number, since it is larger than the sum of its proper divisors (204405).

21043003 is a wasteful number, since it uses less digits than its factorization.

21043003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204404.

The product of its (nonzero) digits is 72, while the sum is 13.

The square root of 21043003 is about 4587.2653073482. The cubic root of 21043003 is about 276.0806098997.

Adding to 21043003 its reverse (30034012), we get a palindrome (51077015).

The spelling of 21043003 in words is "twenty-one million, forty-three thousand, three".