21442320 has 120 divisors (see below), whose sum is σ = 74745216. Its totient is φ = 5712768.

The previous prime is 21442319. The next prime is 21442327. The reversal of 21442320 is 2324412.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21442293 and 21442302.

It is not an unprimeable number, because it can be changed into a prime (21442327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18889 + ... + 19991.

Almost surely, 2^21442320 is an apocalyptic number.

21442320 is a gapful number since it is divisible by the number (20) 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 21442320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37372608).

21442320 is an abundant number, since it is smaller than the sum of its proper divisors (53302896).

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

21442320 is a wasteful number, since it uses less digits than its factorization.

21442320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1131 (or 1113 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 21442320 is about 4630.5852761827. The cubic root of 21442320 is about 277.8160023249.

Adding to 21442320 its reverse (2324412), we get a palindrome (23766732).

The spelling of 21442320 in words is "twenty-one million, four hundred forty-two thousand, three hundred twenty".