21663152 has 40 divisors (see below), whose sum is σ = 48377856. Its totient is φ = 9205056.

The previous prime is 21663149. The next prime is 21663179. The reversal of 21663152 is 25136612.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13463 + ... + 14985.

Almost surely, 2^21663152 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 21663152, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24188928).

21663152 is an abundant number, since it is smaller than the sum of its proper divisors (26714704).

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

21663152 is a wasteful number, since it uses less digits than its factorization.

21663152 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1665 (or 1659 counting only the distinct ones).

The product of its digits is 2160, while the sum is 26.

The square root of 21663152 is about 4654.3691301830. The cubic root of 21663152 is about 278.7664785448.

Adding to 21663152 its reverse (25136612), we get a palindrome (46799764).

The spelling of 21663152 in words is "twenty-one million, six hundred sixty-three thousand, one hundred fifty-two".