21844188 has 48 divisors (see below), whose sum is σ = 56949760. Its totient is φ = 7240752.

The previous prime is 21844187. The next prime is 21844217. The reversal of 21844188 is 88144812.

It is a happy number.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21844187) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23631 + ... + 24537.

Almost surely, 2^21844188 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 21844188, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28474880).

21844188 is an abundant number, since it is smaller than the sum of its proper divisors (35105572).

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

21844188 is a wasteful number, since it uses less digits than its factorization.

21844188 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1143 (or 1135 counting only the distinct ones).

The product of its digits is 16384, while the sum is 36.

The square root of 21844188 is about 4673.7766313764. The cubic root of 21844188 is about 279.5408631770.

The spelling of 21844188 in words is "twenty-one million, eight hundred forty-four thousand, one hundred eighty-eight".