21453424 has 20 divisors (see below), whose sum is σ = 41637960. Its totient is φ = 10708160.

The previous prime is 21453401. The next prime is 21453427. The reversal of 21453424 is 42435412.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21453427) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16842 + ... + 18070.

It is an arithmetic number, because the mean of its divisors is an integer number (2081898).

Almost surely, 2^21453424 is an apocalyptic number.

It is an amenable number.

21453424 is a deficient number, since it is larger than the sum of its proper divisors (20184536).

21453424 is a wasteful number, since it uses less digits than its factorization.

21453424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2328 (or 2322 counting only the distinct ones).

The product of its digits is 3840, while the sum is 25.

The square root of 21453424 is about 4631.7841055041. The cubic root of 21453424 is about 277.8639501300.

Adding to 21453424 its reverse (42435412), we get a palindrome (63888836).

The spelling of 21453424 in words is "twenty-one million, four hundred fifty-three thousand, four hundred twenty-four".