21318603 has 4 divisors (see below), whose sum is σ = 28424808. Its totient is φ = 14212400.

The previous prime is 21318599. The next prime is 21318643. The reversal of 21318603 is 30681312.

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 21318603 - 2² = 21318599 is a prime.

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (21318643) 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 3 ways as a sum of consecutive naturals, for example, 3553098 + ... + 3553103.

It is an arithmetic number, because the mean of its divisors is an integer number (7106202).

Almost surely, 2^21318603 is an apocalyptic number.

21318603 is a deficient number, since it is larger than the sum of its proper divisors (7106205).

21318603 is an equidigital number, since it uses as much as digits as its factorization.

21318603 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7106204.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21318603 is about 4617.2072728003. The cubic root of 21318603 is about 277.2806610257.

Adding to 21318603 its reverse (30681312), we get a palindrome (51999915).

The spelling of 21318603 in words is "twenty-one million, three hundred eighteen thousand, six hundred three".