21368424 has 128 divisors (see below), whose sum is σ = 68935680. Its totient is φ = 5356800.

The previous prime is 21368401. The next prime is 21368429. The reversal of 21368424 is 42486312.

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

It is a junction number, because it is equal to n+sod(n) for n = 21368391 and 21368400.

It is not an unprimeable number, because it can be changed into a prime (21368429) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 57102 + ... + 57474.

It is an arithmetic number, because the mean of its divisors is an integer number (538560).

Almost surely, 2^21368424 is an apocalyptic number.

21368424 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 21368424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34467840).

21368424 is an abundant number, since it is smaller than the sum of its proper divisors (47567256).

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

21368424 is a wasteful number, since it uses less digits than its factorization.

21368424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 431 (or 427 counting only the distinct ones).

The product of its digits is 9216, while the sum is 30.

The square root of 21368424 is about 4622.5992688097. The cubic root of 21368424 is about 277.4964921235.

The spelling of 21368424 in words is "twenty-one million, three hundred sixty-eight thousand, four hundred twenty-four".