21245503 has 8 divisors (see below), whose sum is σ = 21885696. Its totient is φ = 20611200.

The previous prime is 21245489. The next prime is 21245513. The reversal of 21245503 is 30554212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21245503 - 2⁹ = 21244991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6475 + ... + 9187.

It is an arithmetic number, because the mean of its divisors is an integer number (2735712).

Almost surely, 2^21245503 is an apocalyptic number.

21245503 is a deficient number, since it is larger than the sum of its proper divisors (640193).

21245503 is a wasteful number, since it uses less digits than its factorization.

21245503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2945.

The product of its (nonzero) digits is 1200, while the sum is 22.

The square root of 21245503 is about 4609.2844347035. The cubic root of 21245503 is about 276.9633727587.

Adding to 21245503 its reverse (30554212), we get a palindrome (51799715).

The spelling of 21245503 in words is "twenty-one million, two hundred forty-five thousand, five hundred three".