21663296 has 56 divisors (see below), whose sum is σ = 45354240. Its totient is φ = 10252800.

The previous prime is 21663283. The next prime is 21663329. The reversal of 21663296 is 69236612.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 120935 + ... + 121113.

Almost surely, 2^21663296 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 21663296, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22677120).

21663296 is an abundant number, since it is smaller than the sum of its proper divisors (23690944).

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

21663296 is a wasteful number, since it uses less digits than its factorization.

21663296 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283 (or 273 counting only the distinct ones).

The product of its digits is 23328, while the sum is 35.

The square root of 21663296 is about 4654.3845994933. The cubic root of 21663296 is about 278.7670962186.

The spelling of 21663296 in words is "twenty-one million, six hundred sixty-three thousand, two hundred ninety-six".