21315003 has 4 divisors (see below), whose sum is σ = 28420008. Its totient is φ = 14210000.

The previous prime is 21315001. The next prime is 21315013. The reversal of 21315003 is 30051312.

It is a happy number.

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 21315003 - 2¹ = 21315001 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21315001) 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, 3552498 + ... + 3552503.

It is an arithmetic number, because the mean of its divisors is an integer number (7105002).

Almost surely, 2^21315003 is an apocalyptic number.

21315003 is a deficient number, since it is larger than the sum of its proper divisors (7105005).

21315003 is an equidigital number, since it uses as much as digits as its factorization.

21315003 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7105004.

The product of its (nonzero) digits is 90, while the sum is 15.

The square root of 21315003 is about 4616.8174102947. The cubic root of 21315003 is about 277.2650523329.

Adding to 21315003 its reverse (30051312), we get a palindrome (51366315).

The spelling of 21315003 in words is "twenty-one million, three hundred fifteen thousand, three".