21242603 has 4 divisors (see below), whose sum is σ = 21441240. Its totient is φ = 21043968.

The previous prime is 21242591. The next prime is 21242629. The reversal of 21242603 is 30624212.

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 21242603 - 2⁶ = 21242539 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21242203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99158 + ... + 99371.

It is an arithmetic number, because the mean of its divisors is an integer number (5360310).

Almost surely, 2^21242603 is an apocalyptic number.

21242603 is a deficient number, since it is larger than the sum of its proper divisors (198637).

21242603 is a wasteful number, since it uses less digits than its factorization.

21242603 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198636.

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 21242603 is about 4608.9698415156. The cubic root of 21242603 is about 276.9507704004.

Adding to 21242603 its reverse (30624212), we get a palindrome (51866815).

The spelling of 21242603 in words is "twenty-one million, two hundred forty-two thousand, six hundred three".