21818107 has 4 divisors (see below), whose sum is σ = 21827520. Its totient is φ = 21808696.

The previous prime is 21818077. The next prime is 21818117. The reversal of 21818107 is 70181812.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21818107 - 2¹⁵ = 21785339 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21818117) 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, 1494 + ... + 6772.

It is an arithmetic number, because the mean of its divisors is an integer number (5456880).

Almost surely, 2^21818107 is an apocalyptic number.

21818107 is a deficient number, since it is larger than the sum of its proper divisors (9413).

21818107 is an equidigital number, since it uses as much as digits as its factorization.

21818107 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9412.

The product of its (nonzero) digits is 896, while the sum is 28.

The square root of 21818107 is about 4670.9856561544. The cubic root of 21818107 is about 279.4295657040.

Adding to 21818107 its reverse (70181812), we get a palindrome (91999919).

The spelling of 21818107 in words is "twenty-one million, eight hundred eighteen thousand, one hundred seven".