21818688 has 56 divisors (see below), whose sum is σ = 60777120. Its totient is φ = 6888960.

The previous prime is 21818653. The next prime is 21818711. The reversal of 21818688 is 88681812.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

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, 658 + ... + 6638.

Almost surely, 2^21818688 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21818688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30388560).

21818688 is an abundant number, since it is smaller than the sum of its proper divisors (38958432).

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

21818688 is a wasteful number, since it uses less digits than its factorization.

21818688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6015 (or 6005 counting only the distinct ones).

The product of its digits is 49152, while the sum is 42.

The square root of 21818688 is about 4671.0478481814. The cubic root of 21818688 is about 279.4320460160.

The spelling of 21818688 in words is "twenty-one million, eight hundred eighteen thousand, six hundred eighty-eight".