21253424 has 40 divisors (see below), whose sum is σ = 42666912. Its totient is φ = 10250240.

The previous prime is 21253423. The next prime is 21253459. The reversal of 21253424 is 42435212.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21253424.

It is not an unprimeable number, because it can be changed into a prime (21253423) 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, 60032 + ... + 60384.

Almost surely, 2^21253424 is an apocalyptic number.

It is an amenable number.

21253424 is an abundant number, since it is smaller than the sum of its proper divisors (21413488).

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

21253424 is a wasteful number, since it uses less digits than its factorization.

21253424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 485 (or 479 counting only the distinct ones).

The product of its digits is 1920, while the sum is 23.

The square root of 21253424 is about 4610.1435986312. The cubic root of 21253424 is about 276.9977887367.

Adding to 21253424 its reverse (42435212), we get a palindrome (63688636).

The spelling of 21253424 in words is "twenty-one million, two hundred fifty-three thousand, four hundred twenty-four".