21318903 has 8 divisors (see below), whose sum is σ = 31583600. Its totient is φ = 14212584.

The previous prime is 21318889. The next prime is 21318911. The reversal of 21318903 is 30981312.

It is not a de Polignac number, because 21318903 - 2⁶ = 21318839 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 789589 = 21318903 / (2 + 1 + 3 + 1 + 8 + 9 + 0 + 3).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21318923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 394768 + ... + 394821.

It is an arithmetic number, because the mean of its divisors is an integer number (3947950).

Almost surely, 2^21318903 is an apocalyptic number.

21318903 is a deficient number, since it is larger than the sum of its proper divisors (10264697).

21318903 is an equidigital number, since it uses as much as digits as its factorization.

21318903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 789598 (or 789592 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 21318903 is about 4617.2397598565. The cubic root of 21318903 is about 277.2819616707.

The spelling of 21318903 in words is "twenty-one million, three hundred eighteen thousand, nine hundred three".