21436224 has 56 divisors (see below), whose sum is σ = 57351168. Its totient is φ = 7065600.

The previous prime is 21436223. The next prime is 21436229. The reversal of 21436224 is 42263412.

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

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 = 21436194 and 21436203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21436223) 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, 18049 + ... + 19199.

It is an arithmetic number, because the mean of its divisors is an integer number (1024128).

Almost surely, 2^21436224 is an apocalyptic number.

21436224 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 21436224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28675584).

21436224 is an abundant number, since it is smaller than the sum of its proper divisors (35914944).

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

21436224 is a wasteful number, since it uses less digits than its factorization.

21436224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1263 (or 1253 counting only the distinct ones).

The product of its digits is 2304, while the sum is 24.

The square root of 21436224 is about 4629.9269972646. The cubic root of 21436224 is about 277.7896723558.

Adding to 21436224 its reverse (42263412), we get a palindrome (63699636).

The spelling of 21436224 in words is "twenty-one million, four hundred thirty-six thousand, two hundred twenty-four".