21444388 has 48 divisors (see below), whose sum is σ = 45601920. Its totient is φ = 8619264.

The previous prime is 21444373. The next prime is 21444389. The reversal of 21444388 is 88344412.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21444389) 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, 91920 + ... + 92152.

It is an arithmetic number, because the mean of its divisors is an integer number (950040).

Almost surely, 2^21444388 is an apocalyptic number.

21444388 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21444388, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22800960).

21444388 is an abundant number, since it is smaller than the sum of its proper divisors (24157532).

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

21444388 is a wasteful number, since it uses less digits than its factorization.

21444388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 436 (or 434 counting only the distinct ones).

The product of its digits is 24576, while the sum is 34.

The square root of 21444388 is about 4630.8085687059. The cubic root of 21444388 is about 277.8249333396.

The spelling of 21444388 in words is "twenty-one million, four hundred forty-four thousand, three hundred eighty-eight".