21818436 has 24 divisors (see below), whose sum is σ = 51774240. Its totient is φ = 7149312.

The previous prime is 21818431. The next prime is 21818449. The reversal of 21818436 is 63481812.

It is a junction number, because it is equal to n+sod(n) for n = 21818397 and 21818406.

It is not an unprimeable number, because it can be changed into a prime (21818431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14701 + ... + 16116.

It is an arithmetic number, because the mean of its divisors is an integer number (2157260).

Almost surely, 2^21818436 is an apocalyptic number.

It is an amenable number.

21818436 is an abundant number, since it is smaller than the sum of its proper divisors (29955804).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21818436 is a wasteful number, since it uses less digits than its factorization.

21818436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30883 (or 30881 counting only the distinct ones).

The product of its digits is 9216, while the sum is 33.

The square root of 21818436 is about 4671.0208734280. The cubic root of 21818436 is about 279.4309702234.

The spelling of 21818436 in words is "twenty-one million, eight hundred eighteen thousand, four hundred thirty-six".