21153472 has 28 divisors (see below), whose sum is σ = 42382440. Its totient is φ = 10474496.

The previous prime is 21153443. The next prime is 21153481. The reversal of 21153472 is 27435112.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5304 + ... + 8392.

Almost surely, 2^21153472 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21153472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21191220).

21153472 is an abundant number, since it is smaller than the sum of its proper divisors (21228968).

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

21153472 is a wasteful number, since it uses less digits than its factorization.

21153472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3208 (or 3198 counting only the distinct ones).

The product of its digits is 1680, while the sum is 25.

The square root of 21153472 is about 4599.2903800478. The cubic root of 21153472 is about 276.5628784422.

Adding to 21153472 its reverse (27435112), we get a palindrome (48588584).

The spelling of 21153472 in words is "twenty-one million, one hundred fifty-three thousand, four hundred seventy-two".