21045403 has 4 divisors (see below), whose sum is σ = 21066160. Its totient is φ = 21024648.

The previous prime is 21045377. The next prime is 21045421. The reversal of 21045403 is 30454012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21045403 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21045433) 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, 8775 + ... + 10912.

It is an arithmetic number, because the mean of its divisors is an integer number (5266540).

Almost surely, 2^21045403 is an apocalyptic number.

21045403 is a deficient number, since it is larger than the sum of its proper divisors (20757).

21045403 is a wasteful number, since it uses less digits than its factorization.

21045403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20756.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 21045403 is about 4587.5268936541. The cubic root of 21045403 is about 276.0911053643.

Adding to 21045403 its reverse (30454012), we get a palindrome (51499415).

The spelling of 21045403 in words is "twenty-one million, forty-five thousand, four hundred three".