21335424 has 64 divisors (see below), whose sum is σ = 61836480. Its totient is φ = 6464000.

The previous prime is 21335411. The next prime is 21335437. The reversal of 21335424 is 42453312.

It is an interprime number because it is at equal distance from previous prime (21335411) and next prime (21335437).

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a junction number, because it is equal to n+sod(n) for n = 21335394 and 21335403.

It is a congruent number.

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, 1699 + ... + 6749.

It is an arithmetic number, because the mean of its divisors is an integer number (966195).

Almost surely, 2^21335424 is an apocalyptic number.

21335424 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 21335424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30918240).

21335424 is an abundant number, since it is smaller than the sum of its proper divisors (40501056).

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

21335424 is a wasteful number, since it uses less digits than its factorization.

21335424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5079 (or 5067 counting only the distinct ones).

The product of its digits is 2880, while the sum is 24.

The square root of 21335424 is about 4619.0284692779. The cubic root of 21335424 is about 277.3535693650.

Adding to 21335424 its reverse (42453312), we get a palindrome (63788736).

It can be divided in two parts, 2133 and 5424, that added together give a palindrome (7557).

The spelling of 21335424 in words is "twenty-one million, three hundred thirty-five thousand, four hundred twenty-four".