21023603 has 4 divisors (see below), whose sum is σ = 21512568. Its totient is φ = 20534640.

The previous prime is 21023599. The next prime is 21023623. The reversal of 21023603 is 30632012.

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 21023603 - 2² = 21023599 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21023623) 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, 244418 + ... + 244503.

It is an arithmetic number, because the mean of its divisors is an integer number (5378142).

Almost surely, 2^21023603 is an apocalyptic number.

21023603 is a deficient number, since it is larger than the sum of its proper divisors (488965).

21023603 is an equidigital number, since it uses as much as digits as its factorization.

21023603 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 488964.

The product of its (nonzero) digits is 216, while the sum is 17.

The square root of 21023603 is about 4585.1502701656. The cubic root of 21023603 is about 275.9957422504.

Adding to 21023603 its reverse (30632012), we get a palindrome (51655615).

The spelling of 21023603 in words is "twenty-one million, twenty-three thousand, six hundred three".