21442304 has 72 divisors (see below), whose sum is σ = 48933360. Its totient is φ = 9289728.

The previous prime is 21442301. The next prime is 21442307. The reversal of 21442304 is 40324412.

It is an interprime number because it is at equal distance from previous prime (21442301) and next prime (21442307).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21442301) 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, 56387 + ... + 56765.

It is an arithmetic number, because the mean of its divisors is an integer number (679630).

Almost surely, 2^21442304 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 21442304, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24466680).

21442304 is an abundant number, since it is smaller than the sum of its proper divisors (27491056).

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

21442304 is a wasteful number, since it uses less digits than its factorization.

21442304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 425 (or 411 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 21442304 is about 4630.5835485390. The cubic root of 21442304 is about 277.8159332239.

Adding to 21442304 its reverse (40324412), we get a palindrome (61766716).

The spelling of 21442304 in words is "twenty-one million, four hundred forty-two thousand, three hundred four".