21318107 has 4 divisors (see below), whose sum is σ = 21393720. Its totient is φ = 21242496.

The previous prime is 21318091. The next prime is 21318109. The reversal of 21318107 is 70181312.

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 21318107 - 2⁴ = 21318091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21318109) 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, 37382 + ... + 37947.

It is an arithmetic number, because the mean of its divisors is an integer number (5348430).

Almost surely, 2^21318107 is an apocalyptic number.

21318107 is a deficient number, since it is larger than the sum of its proper divisors (75613).

21318107 is an equidigital number, since it uses as much as digits as its factorization.

21318107 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75612.

The product of its (nonzero) digits is 336, while the sum is 23.

The square root of 21318107 is about 4617.1535603660. The cubic root of 21318107 is about 277.2785105990.

Adding to 21318107 its reverse (70181312), we get a palindrome (91499419).

The spelling of 21318107 in words is "twenty-one million, three hundred eighteen thousand, one hundred seven".