21919744 has 96 divisors (see below), whose sum is σ = 55036800. Its totient is φ = 8478720.

The previous prime is 21919741. The next prime is 21919753. The reversal of 21919744 is 44791912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21919741) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 157627 + ... + 157765.

It is an arithmetic number, because the mean of its divisors is an integer number (573300).

Almost surely, 2^21919744 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 21919744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27518400).

21919744 is an abundant number, since it is smaller than the sum of its proper divisors (33117056).

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

21919744 is a wasteful number, since it uses less digits than its factorization.

21919744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179 (or 159 counting only the distinct ones).

The product of its digits is 18144, while the sum is 37.

The square root of 21919744 is about 4681.8526247630. The cubic root of 21919744 is about 279.8627899160.

It can be divided in two parts, 2191 and 9744, that added together give a triangular number (11935 = T₁₅₄).

The spelling of 21919744 in words is "twenty-one million, nine hundred nineteen thousand, seven hundred forty-four".