21424144 has 40 divisors (see below), whose sum is σ = 47729088. Its totient is φ = 9125760.

The previous prime is 21424129. The next prime is 21424159. The reversal of 21424144 is 44142412.

It is an interprime number because it is at equal distance from previous prime (21424129) and next prime (21424159).

It is a super-2 number, since 2×21424144² = 917987892265472, which contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21579 + ... + 22549.

Almost surely, 2^21424144 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 21424144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23864544).

21424144 is an abundant number, since it is smaller than the sum of its proper divisors (26304944).

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

21424144 is a wasteful number, since it uses less digits than its factorization.

21424144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1183 (or 1177 counting only the distinct ones).

The product of its digits is 1024, while the sum is 22.

The square root of 21424144 is about 4628.6222572165. The cubic root of 21424144 is about 277.7374814198.

Adding to 21424144 its reverse (44142412), we get a palindrome (65566556).

The spelling of 21424144 in words is "twenty-one million, four hundred twenty-four thousand, one hundred forty-four".