21523944 has 64 divisors (see below), whose sum is σ = 58464000. Its totient is φ = 6564096.

The previous prime is 21523927. The next prime is 21523949. The reversal of 21523944 is 44932512.

It is not an unprimeable number, because it can be changed into a prime (21523949) 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, 46257 + ... + 46719.

It is an arithmetic number, because the mean of its divisors is an integer number (913500).

Almost surely, 2^21523944 is an apocalyptic number.

21523944 is a gapful number since it is divisible by the number (24) 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 21523944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29232000).

21523944 is an abundant number, since it is smaller than the sum of its proper divisors (36940056).

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

21523944 is a wasteful number, since it uses less digits than its factorization.

21523944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 634 (or 630 counting only the distinct ones).

The product of its digits is 8640, while the sum is 30.

The square root of 21523944 is about 4639.3904772071. The cubic root of 21523944 is about 278.1680746145.

The spelling of 21523944 in words is "twenty-one million, five hundred twenty-three thousand, nine hundred forty-four".