21868544 has 52 divisors (see below), whose sum is σ = 46197240. Its totient is φ = 10321920.

The previous prime is 21868529. The next prime is 21868571. The reversal of 21868544 is 44586812.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (38).

It is a junction number, because it is equal to n+sod(n) for n = 21868498 and 21868507.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 77684 + ... + 77964.

Almost surely, 2^21868544 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 21868544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23098620).

21868544 is an abundant number, since it is smaller than the sum of its proper divisors (24328696).

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

21868544 is an equidigital number, since it uses as much as digits as its factorization.

21868544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 324 (or 302 counting only the distinct ones).

The product of its digits is 61440, while the sum is 38.

The square root of 21868544 is about 4676.3815071057. The cubic root of 21868544 is about 279.6447194578.

The spelling of 21868544 in words is "twenty-one million, eight hundred sixty-eight thousand, five hundred forty-four".